Bottom-side Peterborough saw off Barnsley to pick up their second Championship win in four days.
George Boyd put Posh ahead after 75 seconds, pouncing when Shaun Brisley's header came back off the post.
Tyrone Barnett made it 2-0 when he met Tommy Rowe's cross from the left with a powerful header.
Craig Davies hit the bar for the Tykes but Rowe also slammed a volley against the woodwork as Peterborough went close to adding a third.
Most of the action took place in a frantic first half that also saw Boyd bring a fine save from Barnsley keeper Ben Alnwick and Nathaniel Knight-Percival head inches wide for the visitors from a corner.
As well as Davies' fierce 25-yard strike that rattled the crossbar, Tykes duo Stephen Dawson and Tomas Cywka were off target with shots from outside the area.
The closest Barnsley came to pulling a goal back after the break was when Cywka's crisp shot was saved by Bobby Olejnik, who also kept out a Davies header before the end.
Peterborough held on to follow up Saturday's surprise victory at Hull with another shock success on the road.
Darren Ferguson's men, who lost their first seven games, remain at the foot of the table but are now only two points behind fourth-bottom Sheffield Wednesday.
Barnsley boss Keith Hill: "We didn't deserve anything from this game. I thought Peterborough were excellent value for the points and I thought Boyd was outstanding. He is everything that I want from a player.
"Our performance players didn't perform. I thought our effort deserved a goal but our performance tonight didn't deserve any points.
"We never got the ball moving and we didn't have any urgency. Our players have got to remind themselves of how we got the results earlier in the season. Our passing is better than that we did tonight."
Peterborough manager Darren Ferguson: "It was a great start, Boyd scored early on and he could have got more.
"He gives us energy. I left him out of the side earlier and that is probably what he wanted.
"We have just beaten a good team in Barnsley. They had the majority of possession and we waited and attacked them on the counter-attack.
"The effort put in tonight by the players was fantastic. Throughout the whole squad there's togetherness. The lads have come off the field exhausted. If I can get the commitment they won't have any complaints from me."
Live Text Commentary
Full Time The final whistle is blown by the referee.90:00 +3:17
John Stones produces a cross, Robert Olejnik makes a save.90:00 +1:28 Substitution
Substitution Kane Ferdinand leaves the field to be replaced by Gabriel Zakuani.90:00 +0:48
Shot by Tyrone Barnett from deep inside the penalty area misses to the left of the target.89:22
Foul by Craig Davies on Shaun Brisley, free kick awarded. Robert Olejnik takes the free kick.87:07 Substitution
Substitution George Boyd leaves the field to be replaced by Grant McCann.86:22
Corner from the left by-line taken by Scott Golbourne, clearance by Tyrone Barnett.85:39
The ball is crossed by Martin Cranie, Craig Davies takes a shot. Robert Olejnik makes a save.82:07
Tomasz Cywka concedes a free kick for a foul on Kane Ferdinand. Robert Olejnik takes the free kick.79:33
Inswinging corner taken by David Perkins from the right by-line, save made by Robert Olejnik.78:55
George Boyd has an effort at goal from outside the area which goes wide right of the goal.77:07
Kane Ferdinand gives away a free kick for an unfair challenge on Craig Davies. Free kick crossed right-footed by Tomasz Cywka, Robert Olejnik makes a save.76:18
Free kick awarded for an unfair challenge on David Perkins by George Boyd. Free kick taken by Martin Cranie.75:02 Booking
Booking Mark Little is cautioned.73:50
Free kick awarded for a foul by Kane Ferdinand on Stephen Dawson. The free kick is swung in right-footed by Tomasz Cywka, Mark Little makes a clearance.71:54
Tyrone Barnett concedes a free kick for a foul on Tomasz Cywka. Direct free kick taken by Stephen Dawson.70:11
Nathaniel Knight-Percival concedes a free kick for a foul on Craig Davies. David Perkins crosses the ball in from the free kick, comfortable save by Ben Alnwick.68:35
Scott Golbourne fouled by Mark Little, the ref awards a free kick. Free kick crossed right-footed by Tomasz Cywka from left wing, clearance made by Tyrone Barnett.66:09
Mark Little challenges Scott Golbourne unfairly and gives away a free kick. Scott Golbourne takes the direct free kick.64:57
Ben Alnwick takes the free kick.
Substitution Matty Done is brought on as a substitute for Jacob Mellis.64:57
Corner taken left-footed by George Boyd from the right by-line, free kick awarded for an unfair challenge on Ben Alnwick by Saido Berahino.64:05 Substitution
Substitution Saido Berahino joins the action as a substitute, replacing Emile Sinclair.62:51
Centre by Scott Golbourne, save made by Robert Olejnik.60:31
Tommy Rowe gives away a free kick for an unfair challenge on David Perkins. Stephen Dawson takes the free kick.59:56
Shot from 25 yards from Emile Sinclair. Blocked by Scott Wiseman.57:46 Substitution
Substitution David Perkins joins the action as a substitute, replacing Bobby Hassell.57:33 Substitution
Substitution Chris Dagnall leaves the field to be replaced by Marlon Harewood.57:10
Tomasz Cywka takes a shot. Save by Robert Olejnik.54:41
The ball is delivered by John Stones, save by Robert Olejnik.53:37
The offside flag is raised against Emile Sinclair. Free kick taken by Ben Alnwick.52:25
The referee penalises Jacob Mellis for handball. Nathaniel Knight-Percival takes the direct free kick.50:42
Short corner worked by Jacob Mellis.49:29
Stephen Dawson delivers the ball, Tyrone Barnett manages to make a clearance.48:55
Inswinging corner taken right-footed by Jacob Mellis from the left by-line.47:22
Martin Cranie takes the direct free kick.47:22 Booking
Booking Michael Bostwick receives a yellow card for unsporting behaviour.47:14
Michael Bostwick gives away a free kick for an unfair challenge on Jacob Mellis.46:39
Chris Dagnall produces a right-footed shot from outside the penalty box and misses wide left of the target.46:10
Michael Bostwick has a drilled shot. Save by Ben Alnwick.45:01
The match restarts for the second half.45:00 +1:04 Half time
Half Time The ref blows to signal half-time.45:00 +0:31
Tommy Rowe takes a shot. The official flags Tommy Rowe offside. Ben Alnwick takes the free kick.44:53
Corner taken left-footed by George Boyd from the left by-line, Martin Cranie makes a clearance.44:17
Unfair challenge on Mark Little by Jacob Mellis results in a free kick. The free kick is swung in left-footed by George Boyd, Scott Wiseman makes a clearance.41:32
George Boyd takes a outswinging corner from the left by-line to the near post, Headed effort from deep inside the penalty area by Nathaniel Knight-Percival misses to the left of the goal.40:43
Tomasz Cywka has an effort at goal from outside the area missing to the wide right of the target.40:28
Stephen Dawson takes a shot. Robert Olejnik makes a comfortable save.37:42
The ball is crossed by John Stones, clearance made by Nathaniel Knight-Percival.36:02
Outswinging corner taken from the right by-line by Jacob Mellis, Martin Cranie takes a shot. Robert Olejnik makes a save.35:50
Foul by Michael Bostwick on Tomasz Cywka, free kick awarded. Bobby Hassell takes the direct free kick.33:21
Craig Davies takes a shot.28:52
Mark Little produces a right-footed shot from just outside the box that misses to the right of the net.27:58
Kane Ferdinand concedes a free kick for a foul on Bobby Hassell. Scott Golbourne restarts play with the free kick.26:56
Michael Bostwick takes a shot. Save made by Ben Alnwick.22:06
Stephen Dawson concedes a free kick for a foul on Tommy Rowe. Nathaniel Knight-Percival takes the free kick.19:38
Foul by Stephen Dawson on George Boyd, free kick awarded. Nathaniel Knight-Percival takes the direct free kick.18:25
Tomasz Cywka concedes a free kick for a foul on Mark Little. Craig Alcock takes the free kick.16:49
The ball is swung over by George Boyd, Tyrone Barnett takes a shot. Save made by Ben Alnwick.15:02
Corner taken right-footed by Jacob Mellis, clearance by Tyrone Barnett.13:38
Outswinging corner taken from the right by-line by Jacob Mellis, Chris Dagnall takes a shot. Robert Olejnik makes a comfortable save.12:11
Shot by John Stones from outside the box goes over the target.10:03
Craig Davies concedes a free kick for a foul on Craig Alcock. Robert Olejnik takes the free kick.9:01
The assist for the goal came from Tommy Rowe.9:01 Goal scored
Goal! - Tyrone Barnett - Barnsley 0 - 2 Peterboro Tyrone Barnett finds the back of the net with a headed goal from inside the area. Barnsley 0-2 Peterborough.7:01
Craig Davies fouled by Nathaniel Knight-Percival, the ref awards a free kick. Direct free kick taken by John Stones.6:10
George Boyd takes a shot. Save by Ben Alnwick. Tommy Rowe takes a shot. Save made by Ben Alnwick.5:33
Effort from just outside the box by Scott Golbourne goes over the bar.5:08
Jacob Mellis takes the outswinging corner, clearance made by Craig Alcock.3:01
Mark Little challenges Tomasz Cywka unfairly and gives away a free kick. Free kick taken by Scott Golbourne.1:18
Shaun Brisley provided the assist for the goal.1:18 Goal scored
Goal! - George Boyd - Barnsley 0 - 1 Peterboro George Boyd finds the back of the net with a goal from inside the six-yard box to the bottom right corner of the goal. Barnsley 0-1 Peterborough.1:15
Shaun Brisley produces a header from close range which bounces off the post.0:39
George Boyd takes the outswinging corner, Bobby Hassell makes a clearance.0:00
The ref blows the whistle to start the match.
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