A Ricardo Almeida Santos own goal, and a bullet header from Tom Hopper secured the points for the visitors, who now sit just two points outside of the playoff places.
United were unchanged from the midweek victory over Bury, with Luke Daniels in between the sticks and a back four of Jordan Clarke, David Mirfin, Murray Wallace and Conor Townsend. There was four in the midfield too, as Hakeeb Adelakun, Stephen Dawson, Neal Bishop and Luke Williams retained their places - leaving Kyle Wootton and Paddy Madden to be the Iron’s attacking outlets.
The visitors were keen to stamp their authority early on, but struggled to breach a Peterborough backline which was holding firm. Madden was the first to strike for goal, but he had to settle for a corner, as his long range effort was deflected wide.
Shortly after, Clarke made an overlapping run and sent a dangerous cross into the penalty area. Then following a few ricochets, the ball fell for Williams, albeit unkindly, which resulted in the midfielder snatching at his attempt.
A similar combination down the same flank would create the Iron’s next opening, with Adelakun this time delivering. Wootton found space at the far post, and sent a header goalwards, however he had to watch as the header squirmed inches wide of the post.
United ‘keeper Daniels, who’d been a spectator for the majority of the half, was called into action five minutes before the interval. He had to be alive at his near post to turn away a shot from Leo Da Silva Lopes, who connected with a low driven cross.
There would be one more chance for the Iron though, as Madden and Williams worked an opening on the edge of the box. The Irishman then struck for goal, but was denied by some good handling by Posh stopper Mark Tyler.
However, Graham Alexander’s side couldn’t find a way through the Peterborough defence ahead of the break, and both sides walked off the field level, with the score goalless.
The Iron were almost caught cold after the break, when substitute Aaron Williams fired a strike across goal. Daniels got down to palm it away but, in doing so, turned the ball into the path of the onrushing Lee Angol. It looked as though the striker would tap home, and he would have done if not for a superb last ditch intervention from Wallace.
The Scotsman’s tackle would go on to prove vital as, a matter of minutes later, United got their noses in front. Clarke had been a constant threat down Peterborough’s left throughout the first half, and five minutes after the resumption of play, his influence paid dividends. The full back whipped in a cross which the Posh defence couldn’t deal with, and resulted in defender Almeida Santos slicing into the back of his own net.
The goal gave Alexander’s men an obvious lift and, just after the hour mark, Adelakun had a chance to double the advantage. The winger made a burst through the middle following a defensive mix up, and stabbed the ball towards goal. He couldn’t generate the power to trouble Tyler in the Posh goal though, who gathered comfortably.
Clarke was nearly involved in another Iron goal midway through the second period. He won the ball back on the halfway line, and then made a strong run down the right flank to cross for Madden, who’d darted towards the near post. The striker then flicked the ball across the goal, but it drifted marginally wide.
If Madden was frustrated with his previous attempt, then he certainly made up for it with his next contribution. The number nine crossed on the volley for substitute Hopper and the forward did the rest, thundering a header home from close range to double the Iron’s advantage.
The Iron had opportunities on the break as the game drew to a close, but they wouldn’t add to their two goals. All immaterial though, as Alexander watched his side clinch a fourth league victory on the bounce.
Peterborough United: Tyler, Baldwin, Taylor (Chettle 46), Oztumer (Williams 46), Maddison, Santos, Beautyman, Fox, Lopes, Angol (Coulthirst 69), Nabi.
Substitutes not used: Alnwick, Ntlhe, Zakuani, Gillett.
Scunthorpe United: Daniels, Clarke, Mirfin, Wallace, Townsend, Adelakun (King 88), Bishop, Dawson, Williams, Madden, Wootton (Hopper 61).
Substitutes not used: Anyon, Laird, Sutton, Vose, Burdett.
Attendance: 5,065 (477 away).