Celtic missed out on a valuable Europa League win after conceding a late penalty to allow Udinese a share of the points in Glasgow.
Ki Sung-Yueng put Celtic ahead from the spot, when Gary Hooper was fouled inside the box after just two minutes.
But 83 goalless minutes later Hooper was judged to have fouled Brazilian Neuton inside the box with Almen Abdi slotting home the resultant penalty.
The outcome leaves Celtic bottom of Group I on goal difference.
Manager Neil Lennon had made significant changes to his line-up: with goalkeeper Lukasz Zaluska back in favour having not played since the signing of Fraser Forster in the August transfer window.
DID YOU KNOW?
- The result ended Celtic's run of four consecutive home wins in Europe
- Celtic have not lost in eight games against Serie A opponents at Celtic Park since AC Milan's 1-0 win in 1969
- The match was Udinese's first game in Europe against Scottish opponents
Glenn Loovens and Anthony Stokes were also dropped in favour of Victor Wanyama and Mohamed Bangura, who made his first start.
Within two minutes Hooper found his way into the opposition box, only to be fouled by Joel Ekstrand - the additional assistant behind the goal appearing to confirm the award of a penalty.
The resulting spot-kick was taken by Ki, the Korean coolly executing a perfect strike into the top left hand corner to give Udinese keeper Samir Handanovic no chance.
Having travelled with a weakened squad and without talismanic striker Antonio Di Natale, the Italians appeared to struggle with Celtic's early pace: Zaluska untroubled in the opening 20 minutes of his return to first team action.
The Poland international was called into action in the 22nd minute to deal with a long-range shot from midfielder Emmanuel Badu which he pushed round the post. Midfielder Almen Abdi also forced a save with a shot from 18 yards out six minutes later.
But Hooper delivered an instant reply: finding himself in space 25 yards out and powering a shot towards the Udinese goal, Handanovic forced to parry the ball away to keep the deficit at a single goal.
And despite the inexperience of a team with seven players aged 23 or under, the Italian side held on until the break: Ki closest to extending Celtic lead with a free kick 20 yards out in the 37th minute which he sent wide.
Joe Ledley failed to emerge for the second half and was replaced by Mark Wilson who was forced to adapt to a game still being played at blistering pace.
Celtic looked in no real danger of losing their lead until in the 62nd minute Medhi Benatia had the ball in the net from Cristian Battochio's chipped free-kick 30 yards but amid more confusion referee Bulent Yildirim consulted his lineman and ruled that Benatia was offside.
The home side increased their attacking options with the introduction of Georgios Samaras and there were late chances for Ki at one end and Mauricio Isla at the other, who forced a tremendous save from Zaluska with six minutes remaining.
“I don't know what the referee was thinking. It's a shocking decision. But I'm delighted with the team”
But Celtic's undoing was to be beyond the keeper's control, Hooper appearing to body-check Udinese defender Neuton inside the box with Lennon's side just minutes from victory. On this occasion the referee Yildirim had no hesistation in pointing to the post, with Abdi slotting the ball into the net to level the tie.
Celtic had an opportunity to rescue the game in the dying seconds when Samaras was fouled just outside the box, but Mulgrew's left-footed effort was parried clear to end the Glasgow side's hopes of a first win in Europe this season.
Live Text Commentary
Full Time The referee brings the game to a close.90:00 +0:18
Free kick awarded for a foul by Mehdi Benatia on Georgios Samaras. Charlie Mulgrew fires a strike on goal direct from the free kick, save by Samir Handanovic.89:05
A cross is delivered by Mohamed Bangura, Georgios Samaras challenges Samir Handanovic unfairly and gives away a free kick. Samir Handanovic takes the direct free kick.87:08 Goal scored
Goal! - Almen Abdi - Celtic 1 - 1 Udinese Almen Abdi scores a power penalty. Celtic 1-1 Udinese.86:25
Penalty awarded for an unfair challenge on Piccoli Neuton by Gary Hooper.86:01
Corner taken by Pablo Armero.85:38
Mauricio Isla takes a shot. Save by Lukasz Zaluska.85:12
Inswinging corner taken by Charlie Mulgrew from the right by-line, save made by Samir Handanovic.84:51
Shot from 20 yards from Sung-Yeung Ki. Fantastic save by Samir Handanovic.83:53
Almen Abdi produces a right-footed shot from just outside the area that goes harmlessly over the bar.82:13
Mauricio Isla has an effort direct from the free kick, Lukasz Zaluska makes a save. Corner taken right-footed by Mauricio Isla, clearance made by Beram Kayal.82:13 Booking
Booking Georgios Samaras goes into the book for persistent infringement.82:03
Unfair challenge on Piccoli Neuton by Georgios Samaras results in a free kick.80:33
Free kick awarded for an unfair challenge on Gary Hooper by Larangera Danilo. Direct free kick taken by Daniel Majstorovic.79:18
Indirect free kick taken by Lukasz Zaluska.79:18 Booking
Booking The referee shows Victor Wanyama a yellow card for persistent infringement.78:59
Mauricio Isla crosses the ball. Pablo Armero is caught offside.77:21
Mauricio Isla produces a cross, Mark Wilson makes a clearance.76:39
Joel Ekstrand fouled by Georgios Samaras, the ref awards a free kick. Free kick taken by Piccoli Neuton.75:12
Corner from the right by-line taken by Mauricio Isla, Headed effort from inside the box by Larangera Danilo misses to the right of the target.
Centre by Mauricio Isla, blocked by Charlie Mulgrew.73:30
Shot from 20 yards from Mark Wilson. Joel Ekstrand gets a block in.73:24
Adam Matthews produces a cross, Larangera Danilo makes a clearance.73:13
Beram Kayal produces a cross, clearance made by Larangera Danilo.70:59
Larangera Danilo takes the free kick.70:59 Substitution
Substitution Georgios Samaras comes on in place of James Forrest.70:59
Victor Wanyama challenges Pablo Armero unfairly and gives away a free kick.69:47
Sung-Yeung Ki delivers the ball from the free kick right-footed from right channel.69:47 Booking
Booking Joel Ekstrand goes into the referee's book.69:30
Foul by Joel Ekstrand on Mohamed Bangura, free kick awarded.69:22
Centre by Mohamed Bangura, Mehdi Benatia manages to make a clearance.68:29
Gary Hooper fouled by Mehdi Benatia, the ref awards a free kick. Charlie Mulgrew takes the free kick.67:43
Beram Kayal concedes a free kick for a foul on Piccoli Neuton. Free kick taken by Piccoli Neuton.67:24
The ball is swung over by Sung-Yeung Ki, save by Samir Handanovic.65:54
The free kick is swung in right-footed by Sung-Yeung Ki.65:54 Substitution
Substitution Diego Fabbrini goes off and Pablo Armero comes on.65:54
Foul by Mehdi Benatia on Mohamed Bangura, free kick awarded.61:35
Victor Wanyama challenges Diego Fabbrini unfairly and gives away a free kick. The ball is delivered by Cristian Battocchio, Mehdi Benatia takes a shot. The assistant referee signals for offside against Mehdi Benatia. Free kick taken by Lukasz Zaluska.57:24
Emmanuel Agyemang-Badu produces a cross, Almen Abdi has an effort at goal from deep inside the area missing to the left of the goal.56:31
Corner taken by Mauricio Isla.56:18
Diego Fabbrini crosses the ball, clearance made by Adam Matthews.55:26
Unfair challenge on Gary Hooper by Tape Doubai results in a free kick. Daniel Majstorovic restarts play with the free kick.54:28
Free kick awarded for an unfair challenge on Joel Ekstrand by Mohamed Bangura. Cristian Battocchio takes the direct free kick.53:55
The ball is swung over by Mohamed Bangura.52:37
Mehdi Benatia concedes a free kick for a foul on Gary Hooper. Sung-Yeung Ki restarts play with the free kick.51:01
Shot on goal comes in from Charlie Mulgrew from the free kick, save by Samir Handanovic.51:01 Booking
Booking Booking for Emmanuel Agyemang-Badu for persistent infringement.50:59
Emmanuel Agyemang-Badu gives away a free kick for an unfair challenge on James Forrest.50:26
Beram Kayal challenges Diego Fabbrini unfairly and gives away a free kick. Piccoli Neuton restarts play with the free kick.49:42
The referee blows for offside against Almen Abdi. Free kick taken by Daniel Majstorovic.48:34
Mehdi Benatia is caught offside. Lukasz Zaluska restarts play with the free kick.48:02
Sung-Yeung Ki challenges Emmanuel Agyemang-Badu unfairly and gives away a free kick. Mauricio Isla takes the free kick.47:03
Piccoli Neuton gives away a free kick for an unfair challenge on Mark Wilson. Lukasz Zaluska takes the free kick.45:01
The second half begins.45:01
Diego Fabbrini is penalised for handball and concedes a free kick. Lukasz Zaluska takes the direct free kick.45:01 Substitution
Substitution Joe Ledley goes off and Mark Wilson comes on.45:01 Substitution
Substitution Mauricio Isla replaces Roberto Pereyra.45:01 Substitution
Substitution Mehdi Benatia on for Dusan Basta.45:00 +1:01 Half time
Half Time The ref blows to signal half-time.43:58
Shot from 18 yards from James Forrest.43:01
Unfair challenge on Beram Kayal by Diego Fabbrini results in a free kick. Free kick taken by Daniel Majstorovic.42:15
Free kick awarded for an unfair challenge on Emmanuel Agyemang-Badu by Joe Ledley. Emmanuel Agyemang-Badu takes the direct free kick.40:05
Free kick awarded for a foul by Joe Ledley on Roberto Pereyra. Direct free kick taken by Dusan Basta.38:43
Adam Matthews sends in a cross, save made by Samir Handanovic.36:14
Tape Doubai challenges Mohamed Bangura unfairly and gives away a free kick. Sung-Yeung Ki produces a shot on goal direct from the free kick.35:40
James Forrest delivers the ball.35:08
Charlie Mulgrew takes the inswinging corner, Tape Doubai manages to make a clearance.34:24
Centre by James Forrest, Larangera Danilo manages to make a clearance.33:57
Gary Hooper gives away a free kick for an unfair challenge on Roberto Pereyra. Cristian Battocchio takes the direct free kick.32:12
Shot from just outside the area by Piccoli Neuton goes over the bar.30:21
Centre by Adam Matthews.29:19
Gary Hooper produces a drilled right-footed shot from 18 yards. Save by Samir Handanovic.28:24
Shot by Almen Abdi from 20 yards. Save by Lukasz Zaluska.24:45
Free kick awarded for an unfair challenge on Dusan Basta by Mohamed Bangura. Larangera Danilo takes the free kick.23:40
Free kick awarded for a foul by Beram Kayal on Emmanuel Agyemang-Badu. Larangera Danilo takes the direct free kick.23:40 Booking
Booking Beram Kayal is given a yellow card.23:21
Centre by Sung-Yeung Ki, Larangera Danilo manages to make a clearance.22:34
Free kick awarded for a foul by Roberto Pereyra on Mohamed Bangura. Direct free kick taken by Charlie Mulgrew.22:03
Outswinging corner taken by Piccoli Neuton from the left by-line, Sung-Yeung Ki manages to make a clearance.21:45
Emmanuel Agyemang-Badu takes a shot. Save made by Lukasz Zaluska.19:27
Diego Fabbrini fouled by Beram Kayal, the ref awards a free kick. Cristian Battocchio crosses the ball from the free kick right-footed from left wing, Lukasz Zaluska makes a save.18:59
Beram Kayal gives away a free kick for an unfair challenge on Piccoli Neuton. Direct free kick taken by Piccoli Neuton.18:35
Roberto Pereyra challenges Joe Ledley unfairly and gives away a free kick. Charlie Mulgrew takes the free kick.17:59
Free kick awarded for a foul by Mohamed Bangura on Dusan Basta. Larangera Danilo restarts play with the free kick.17:30
Diego Fabbrini gives away a free kick for an unfair challenge on Adam Matthews. Adam Matthews takes the free kick.16:49
Unfair challenge on Mohamed Bangura by Tape Doubai results in a free kick. Direct free kick taken by Charlie Mulgrew.16:09
Dusan Basta concedes a free kick for a foul on Mohamed Bangura. Charlie Mulgrew takes the direct free kick.15:52
The ball is swung over by Roberto Pereyra, clearance made by Daniel Majstorovic.15:11
Free kick awarded for a foul by Victor Wanyama on Diego Fabbrini. Joel Ekstrand takes the free kick.14:55
Shot from 30 yards from Beram Kayal. Blocked by Larangera Danilo.14:32
A cross is delivered by Adam Matthews.12:34
Almen Abdi is caught offside. Daniel Majstorovic takes the indirect free kick.11:38
Adam Matthews delivers the ball.10:31
James Forrest delivers the ball, Larangera Danilo makes a clearance.7:15
Unfair challenge on Gary Hooper by Emmanuel Agyemang-Badu results in a free kick. Direct free kick taken by Joe Ledley.6:21
Emmanuel Agyemang-Badu challenges Sung-Yeung Ki unfairly and gives away a free kick. Daniel Majstorovic takes the direct free kick.5:15
Almen Abdi gives away a free kick for an unfair challenge on Sung-Yeung Ki. Daniel Majstorovic takes the direct free kick.4:41
Free kick awarded for a foul by Charlie Mulgrew on Diego Fabbrini. Emmanuel Agyemang-Badu takes the direct free kick.3:46
Emmanuel Agyemang-Badu produces a cross, Victor Wanyama makes a clearance.2:59 Goal scored
Goal! - Sung-Yeung Ki - Celtic 1 - 0 Udinese Power penalty scored by Sung-Yeung Ki. Celtic 1-0 Udinese.1:47
Larangera Danilo challenges Gary Hooper unfairly and gives away a Penalty.1:15
Gary Hooper sends in a cross, clearance by Larangera Danilo.0:00
The referee gets the match started.
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