A Kris Commons hat-trick helped Celtic ease past St Johnstone into the semi-final of the Scottish Communities League Cup.
Commons struck twice in five first-half minutes before he created the third goal for Gary Hooper.
The Scotland international scored his third from the penalty spot after Tony Watt was fouled in the second-half.
Charlie Mulgrew blazed in a fifth shortly after as Celtic cruised to a place in the next round.
Celtic closed the top tier of their 60,000-capacity stadium and the bottom section was far from full but Commons did his best to entertain the 14,399 who had braved a miserable night.
His personal duel with Alan Mannus began after 10 minutes when the Saints goalkeeper pulled off a good block from the Parkhead playmaker's long-distance drive, before making an easier save when Commons tried to curl the ball past him moments later.
With the Perth side doing little offensively aside from launching long balls to lone striker Gregory Tade, Celtic continued to dominate possession.
In the 21st minute, after Saints midfielder Murray Davidson had bundled Hooper to the ground 30 yards from goal, Commons' deflected free-kick deceived Mannus before the Perth keeper grabbed the ball at the second attempt.
Moments later the St Johnstone number one was again forced to save from Commons' 30-yard-drive, the Saints defence smuggling the ball out of the box after the keeper failed to hold.
The former Nottingham Forest and Derby player had yet another attempt from outside the box and this time his shot went wide of the far post.
Commons eventually made the breakthrough albeit with the help of Liam Craig whose attempt at blocking the angled-drive succeeded only in taking the ball past Mannus and into the roof of the net.
There was no doubt about Celtic's second goal which followed soon afterwards. Mikael Lustig's pass from wide on the right found Hooper who quickly played in Commons and he drilled his shot low past the helpless Mannus from 12 yards.
Steve Lomas's men looked sapped of all belief as Celtic piled forward at will.
In the 38th minute Lustig had a header cleared off the line by Steven Anderson after McCracken had inadvertently headed against his own crossbar.
A minute later the tie was effectively over when Hooper, in typical poacher's fashion, was on hand to knock Commons' pass past Mannus, who was left exposed once again.
In the 56th minute Celtic were awarded a penalty when Anderson fouled Watt and Commons, almost inevitably, stepped up to slam his spot-kick past Mannus.
It had become a matter of how many Celtic would score and just after the hour mark Mulgrew - who had replaced Hooper at half-time - made it 5-0 after more indecision in the ragged McDiarmid Park defence had allowed the Hoops utility player to find a yard before shooting into the far corner.
The shell-shocked visitors were all over the place and there was a moment of farce when McCracken almost put the ball into his own net trying to usher a Watt cross away from Mannus.
Celtic kept pushing for more goals but five minutes from time, Nigel Hasselbaink, on for Gregory Tade, struck the outside of the post, depriving the visitors of a consolation goal.
Celtic manager Neil Lennon:
"I got everything I wanted. It was a fantastic response.
"It was a difficult couple of days for myself, scratching my head as to where that performance (against Killie) came from but we were back to our best and some of the football and the pace they played at was of a very high order.
"It was a big game, St Johnstone were going very well so to win the game so emphatically was testament to the quality of the players and their attitude.
"We moved the ball around quickly, we were aggressive in our pressing and tackling and that is the sort of team I want to see week-in, week-out.
"I enjoyed watching the team tonight and I hope that is a marker for, I hope, a concerted period of good performances, that is what I am demanding from the team."
St Johnstone manager Steve Lomas:
"Celtic were a class apart. You have to give them credit.
"They showed why they are champions of Scotland and were able to go to Barcelona and give them a game.
Chris Millar takes a shot. Save by Fraser Forster.
Emilio Izaguirre concedes a free kick for a foul on Nigel Hasselbaink. Direct strike on goal from the free kick comes in from Liam Craig.
Booking Booking for Mikael Lustig for unsporting behaviour.
Booking Nigel Hasselbaink receives a yellow card for unsporting behaviour.
Nigel Hasselbaink concedes a free kick for a foul on Mikael Lustig. Fraser Forster takes the free kick.
Nigel Hasselbaink takes a shot. Save by Fraser Forster. Corner taken by Liam Craig from the right by-line, clearance by Joe Ledley.
Liam Craig takes a outswinging corner to the near post, clearance made by Victor Wanyama. David Robertson takes a shot. Blocked by Joe Ledley. Inswinging corner taken by Nigel Hasselbaink from the left by-line, Kevin Moon produces a right-footed shot from deep inside the penalty box which goes wide of the left-hand post.
Nigel Hasselbaink decides to take the corner short.
The free kick is swung in left-footed by Kris Commons, Steven Anderson manages to make a clearance.
Booking Gary Miller is shown a yellow card for unsporting behaviour.
Free kick awarded for a foul by Gary Miller on Patrick McCourt.
Adam Matthews takes a shot. Blocked by Liam Craig. Corner taken short by Adam Matthews.
Inswinging corner taken by Liam Craig from the right by-line, clearance made by Charlie Mulgrew. Effort on goal by Kevin Moon from just inside the area clears the bar.
The ball is crossed by Emilio Izaguirre, Alan Mannus makes a save.
Substitution Nigel Hasselbaink on for Gregory Tade.
A cross is delivered by Gregory Tade, Mikael Lustig manages to make a clearance. Corner from the left by-line taken by Liam Craig, clearance by Adam Matthews.
Substitution Efe Ambrose leaves the field to be replaced by Patrick McCourt.
The official flags Steven MacLean offside. Direct free kick taken by Kelvin Wilson. Kris Commons takes a short corner.
Charlie Mulgrew crosses the ball, Alan Mannus makes a save.
Tony Watt crosses the ball, clearance made by David McCracken. Outswinging corner taken from the left by-line by Kris Commons, David MacKay makes a clearance.
A cross is delivered by Adam Matthews, Shot by Kris Commons. Save by Alan Mannus.
Substitution Adam Matthews joins the action as a substitute, replacing Scott Brown.
Substitution Murray Davidson goes off and David Robertson comes on.
Long range effort by Liam Craig goes wide right of the net.
Assist by Mikael Lustig.
60:24 Goal scored
Goal! - Charlie Mulgrew - Celtic 5 - 0 St J'stone Charlie Mulgrew scores a goal from inside the penalty box to the bottom right corner of the goal. Celtic 5-0 St Johnstone.
Mikael Lustig delivers the ball,
The referee blows for offside against Steven MacLean. Emilio Izaguirre restarts play with the free kick.
Kris Commons takes a shot. Alan Mannus makes a save.
The ball is delivered by Tony Watt.
Shot from just outside the box by Joe Ledley misses to the right of the target.
The assist for the goal came from Tony Watt. Free kick awarded for a foul by Murray Davidson on Tony Watt. Direct free kick taken by Kris Commons.
56:13 Goal scored
Goal! - Kris Commons - Celtic 4 - 0 St J'stone Kris Commons scores a power penalty. Celtic 4-0 St Johnstone.
Booking Booking for Steven Anderson.
Penalty awarded for an unfair challenge on Tony Watt by Steven Anderson.
Corner taken short by Kris Commons. Kris Commons produces a cross, clearance by Liam Craig. Inswinging corner taken from the left by-line by Kris Commons.
Inswinging corner taken left-footed by Kris Commons, David MacKay manages to make a clearance.
Free kick awarded for an unfair challenge on Chris Millar by Tony Watt. David McCracken restarts play with the free kick. Kevin Moon fouled by Scott Brown, the ref awards a free kick. David McCracken takes the direct free kick.
David MacKay takes the free kick.
Booking Efe Ambrose goes into the book.
Efe Ambrose concedes a free kick for a foul on Liam Craig.
Direct free kick taken by Alan Mannus.
Booking The referee shows Tony Watt a yellow card for unsporting behaviour.
Free kick awarded for a foul by Tony Watt on David McCracken.
Foul by Murray Davidson on Kelvin Wilson, free kick awarded. Kris Commons takes the free kick. Steven MacLean challenges Kris Commons unfairly and gives away a free kick. Free kick taken by Charlie Mulgrew.
The ball is swung over by David MacKay, Efe Ambrose manages to make a clearance.
David McCracken delivers the ball, save by Fraser Forster.
The game restarts for the second half.
Substitution Rowan Vine leaves the field to be replaced by Steven MacLean.
Substitution Gary Hooper leaves the field to be replaced by Charlie Mulgrew.
45:00 +0:04 Half time
Half Time The half-time whistle blows.
Joe Ledley gives away a free kick for an unfair challenge on Gregory Tade. Direct free kick taken by Gary Miller.
Liam Craig crosses the ball, Mikael Lustig manages to make a clearance.
Free kick awarded for a foul by Efe Ambrose on Rowan Vine. Liam Craig restarts play with the free kick.
Effort on goal by Tony Watt from 18 yards. Clearance by Steven Anderson.
Tony Watt produces a cross, save by Alan Mannus.
The assist for the goal came from Kris Commons.
37:47 Goal scored
Goal! - Gary Hooper - Celtic 3 - 0 St J'stone Gary Hooper gets on the score sheet with a goal from close range low into the middle of the goal. Celtic 3-0 St Johnstone.
A cross is delivered by Emilio Izaguirre, Mikael Lustig takes a shot. Steven Anderson manages to make a clearance.
Kris Commons decides to take the corner short.
The ball is swung over by Kris Commons.
Corner from the left by-line taken by Liam Craig, clearance made by Efe Ambrose.
Foul by Scott Brown on Liam Craig, free kick awarded. David MacKay takes the free kick.
Booking David MacKay is shown a yellow card.
Assist by Gary Hooper.
31:36 Goal scored
Goal! - Kris Commons - Celtic 2 - 0 St J'stone Kris Commons finds the back of the net with a goal from close in to the bottom left corner of the goal. Celtic 2-0 St Johnstone.
Liam Craig is penalised for handball and concedes a free kick. Victor Wanyama takes the free kick.
The assist for the goal came from Mikael Lustig.
27:03 Goal scored
Goal! - Kris Commons - Celtic 1 - 0 St J'stone A goal is scored by Kris Commons from deep inside the penalty box to the top left corner of the goal. Celtic 1-0 St Johnstone.
A cross is delivered by Emilio Izaguirre, clearance by David MacKay.
David MacKay handles the ball and concedes a free kick. Kris Commons restarts play with the free kick. Gary Hooper takes a shot. Liam Craig gets a block in. Kris Commons takes a inswinging corner to the near post, Liam Craig makes a clearance.
Shot from just outside the penalty box by Kris Commons misses to the left of the target.
Kris Commons produces a drilled left-footed shot from 12 yards. Save by Alan Mannus.
Mikael Lustig crosses the ball, David MacKay manages to make a clearance.
Murray Davidson challenges Gary Hooper unfairly and gives away a free kick. Shot on goal comes in from Kris Commons from the free kick, save by Alan Mannus.
Corner from the left by-line taken by Kris Commons, clearance by David McCracken.
The ball is delivered by Liam Craig, clearance by Emilio Izaguirre.
Tony Watt fouled by Murray Davidson, the ref awards a free kick. Free kick taken by Joe Ledley.
Gary Hooper produces a right-footed shot from just outside the box that misses to the right of the net.
The ball is sent over by Emilio Izaguirre.
The ball is sent over by Scott Brown, Steven Anderson makes a clearance.
A cross is delivered by Tony Watt, clearance made by Steven Anderson.
Kris Commons takes a shot. Alan Mannus makes a save. Kris Commons takes the chance to get an effort at goal. Save by Alan Mannus.
Corner taken by Kris Commons from the right by-line, clearance by David McCracken.
Corner taken by Liam Craig, save made by Fraser Forster.
Foul by Gregory Tade on Victor Wanyama, free kick awarded. Fraser Forster takes the free kick.
Inswinging corner taken left-footed by Kris Commons, Headed effort from inside the area by Victor Wanyama misses to the left of the goal. Unfair challenge on Efe Ambrose by Gregory Tade results in a free kick. Efe Ambrose takes the free kick.
Unfair challenge on Liam Craig by Emilio Izaguirre results in a free kick. Free kick taken by Steven Anderson.
The ball is crossed by Kris Commons, David McCracken makes a clearance.
The ball is sent over by Tony Watt, Steven Anderson manages to make a clearance.
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