A LAPSE in concentration proved hugely costly for Oxford United as their five-game unbeaten run was ended by Peterborough United in a poor game.

Ivan Toney netted the only goal late in the contest, running on to Marcus Maddison’s free-kick and scoring while the home side’s defence dozed.

It settled a game where United fell short of their recent performance levels and rarely looked like scoring.

They finished the game with ten men after Gavin Whyte came off with an injury after the U’s had made all three substitutions.

And defeat meant Karl Robinson’s side slipped back into the Sky Bet League One relegation zone ahead of Tuesday night’s visit to Accrington Stanley.

Jerome Sinclair replaced Jamie Mackie in the only change to the starting line-up from last week’s draw with Sunderland.

Mark Sykes was not fit enough to make the bench, so his place was taken by Nico Jones, 17, who was named in the squad for the first time.

Peterborough arrived struggling for form, but came flying out of the traps.

They forced three corners inside the first three minutes, two of which were caught by Simon Eastwood.

The U’s goalkeeper was beaten in the fifth minute, but after collecting Kyle Dempsey’s ball over Jordan Graham, Jason Naismith’s shot rattled the near post and rebounded to safety.

Marcus Maddison was causing the hosts problems in a free role, but when he went down in the 11th minute looking for a free-kick, referee Ross Joyce did not buy it.

United sprung forward and eventually saw Gavin Whyte cut the ball back for Cameron Brannagan, who fired wide from 15 yards.

Whyte was involved again midway through the half, but when he went down in the box under Alex Woodyard’s challenge, the referee was unmoved.

United’s protests were muted, which went along with a flat atmosphere which was in stark contrast to the mood in the Kassam Stadium a week earlier.

Peterborough were forced into a defensive reshuffle when debutant Josh Knight came off with an injury, replaced by Ryan Tafazolli.

When the game settled down, there was little to choose between the sides, who were not suited to the deteriorating playing surface.

Maddison remained Peterborough’s main threat and six minutes before the break his free-kick laid on a glorious chance for Ivan Toney, who let the U’s off the hook by heading wide.

At the other end, Josh Ruffels volleyed over a corner from Brannagan, who finally tested Posh goalkeeper Conor O’Malley late in the half with a stinging shot from the edge of the penalty area.

Peterborough started the second half brightly without testing Eastwood, before the game slipped back into a scrappy affair.

One terrific Whyte burst down the right took him past two defenders, but from his low cross Henry missed his kick in the box.

Just after the hour mark O’Malley made a smart parry to deny Jamie Hanson’s low left-footed effort from the edge of the box. Sinclair appeared to be pulled down as he went for the rebound, but the referee waved away the protests.

Both sides turned to their benches for inspiration. Lee Tomlin came on for the visitors, while Marcus Browne and Mackie added fresh legs to the United cause.

But what they needed were fresh minds, as 14 minutes from time the hosts went to sleep over a Maddison free-kick. The Posh forward was on the same wavelength as Toney, though, who ran unnoticed on to the pass before lashing a shot past Eastwood.

United had come from behind late on to draw with Sunderland a week earlier, but here they did not threaten a dramatic finish.

They were not helped by finishing the game with ten men. Having made their three substitutions, Whyte came off second best in a fair challenge from Ben White and could not continue.

Their biggest hopes late on came from penalty shouts. United looked to have a case when Browne went down deep into stoppage-time, but the referee only awarded a corner.

Oxford Utd (4-2-3-1): Eastwood, Hanson, Nelson, Dickie, Ruffels, Mousinho (Carruthers 79), Brannagan, Henry (Browne 68) Whyte, Sinclair (Mackie 68), Graham.

Unused subs: Stevens, Long, Jones, Kashi.

Booked: Hanson, Dickie, Browne.

Peterborough Utd (4-1-2-1-2): O’Malley, Naismith, Knight (Tafazolli 22), White, Lafferty (Bennett 71), Woodyard, Ward, Dempsey, Cooper (Tomlin 59), Maddison, Toney.

Unused subs: Chapman, Reed, Godden, Stevens.

Booked: White, Maddison, Woodyard.

Attendance: 6,457 (490 visitors).

Referee: Ross Joyce (Cleveland).