CHRIS Maguire's dramatic penalty three minutes into stoppage time gave Oxford United a first Sky Bet League One victory of the season.

The U's man held his nerve to fire into the back of the net after he had been fouled by Jack Baldwin.

The Peterborough defender was sent off for a second yellow card, but the coolest man in the Kassam Stadium was Maguire, who slotted home as the home crowd erupted.

It had looked as though Michael Apppleton's side would have to wait for their first league win.

As in the opening home game of their campaign, United took the lead, but saw their visitors hit back.

Wes Thomas fired United ahead just 13 seconds into the second period, but a Tom Nichols strike on 62 minutes drew Peterborough levelled the score.

The U's had goalkeeper Simon Eastwood to thank for keeping them level, showing superb reactions to stop Josh Ruffels from scoring an own goal three minutes from time.

Adil Nabi's cross from left hit the United man and Eastwood somehow clawed the ball back.

It looked like some of the ball has crossed the line, but the officials waved play on.

Home fans felt relieved and would happily have taken a point, before Maguire stepped up to give them all three.

Head coach Appleton made three changes from the side that lost at Fleetwood in midweek.

Phil Edwards was handed a debut at right back after signing on a season-long loan from Burton Albion on Friday, while Ruffels and Thomas also came into the XI at the expense of Aaron Martin and Ryan Taylor.

Ruffels slotted in to the left back position, with Joe Skarz moving to left-side centre half with Aaron Martin dropped.

Peterborough named an unchanged side after thumping highly-fancied Millwall 5-1 in midweek.

Both sides will be happy with their start, although neither was able to find any clear openings.

The visitors looked dangerous, with their front players all finding pockets of space between the U's lines.

They went slightly more direct to create the opening chance.

Michael Smith got in behind Ruffels and although his cross was behind onrushing teammates, the ball got played back to Chris Forrester whose shot from 20 yards was blocked by the United defence.

Both sides looked lively though and a Ruffels cross was just too high for Kane Hemmings who headed over on ten minutes.

With drizzle falling, the surface was greasy and several passes skipped away from their intended targets.

The first effort on target came from Posh skipper Forrester who fired straight at Eastwood from 20 yards.

A comical spell from referee Sebastian Stockbridge then followed when he awarded a corner to Peterborough after Andrew Hughes headed wide, and from another Posh corner, Wes Thomas deflected the ball behind and he gave a goal kick.

On 29 minutes the U's were grateful to their goalkeeper for keeping them on level terms.

Chris Maguire gave the ball away on the edge of his own box and a shot from Gwion Edwards was deflected, forcing the U's keeper to produce a fine reaction save and tip over.

Eastwood got down well to hold on to another Gwion Edwards effort as several more bizarre decisions from the offical stopped the flow of the game.

Mr Stockbridge had given 17 yellow cards in his opening four games of the season, and he was determined to maintain his high volume of cautions.

Three Peterborough players went in his book, with Liam Sercombe and Skarz joining them.

United's front two were getting little change out of Peterborough's back line, too often a misplaced pass or lack of pace proving their undoing.

But just 13 seconds into the second half it all went right.

Peterborough kicked off but lost the ball and when Thomas picked it up just inside the box, he twisted before firing in a shot that deflected past Ben Alnwick and into the net.

It was just the opening United wanted and they started to play with plenty of confidence.

John Lundstram twice fired on effort narrowly off target.

But on 53 minutes United were saved by their keeper after a flowing Posh move.

A ball into the box from Gwion Edwards found Jermaine Anderson, who took a touch and got in a shot that Eastwood did well to smother after racing off his line.

Paul Taylor was the next visiting player to break into the U's area, but he blasted high and wide.

A fine cross from Phil Edwards looked destined for the head of Thomas, but Baldwin nodded clear.

And moments later the visitors levelled.

Some delicate passing from Peterborough saw them break into the U's box and when the ball ended at the feet of Tom Nichols, he fired into the roof of the net from eight yards.

The visitors seized the initiative and caused United's back line plenty of problems.

But they stayed firm and gradually got back into the game.

They won a succession of corners, and from one Chey Dunkley headed goalwards, and a huge scramble followed, but the U's could not force the ball home.

Tyler Roberts, Ryan Taylor and Dan Crowley were all introduced as United looked for the all-important third goal.

Roberts and Taylor combined to start a move that saw Maguire play in Sercombe, but his shot went into the side netting.

Eastwood then produced his stunning stop to keep the scores level, before a dramatic finish saw Maguire take centre stage with his spot-kick.

United are up and running, and how.

Oxford Utd (4-4-2): Eastwood, P Edwards, Dunkley, Skarz, Ruffels, MacDonald (T Roberts 68), Lundstram, Sercombe, Maguire, Thomas (Crowley 81), Hemmings (R Taylor 77).

Subs not used: Long, Martin, Rothwell, Buchel.

Booked: Sercombe, Skarz.

Peterborough Utd (4-2-3-1): Alnwick, Smith, Baldwin, Bostwick, Hughes, Maddison (Nabi 73), Forrester (Da Silva Lopez 63), J Anderson, G Edwards, P Taylor (Coulthurst 77), Nichols. Subs not used: Santos, White, Gormley, Tyler.

Booked: G Edwards, Baldwin, Forrester, Da Silva Lopez.

Referee: Sebastian Stockbridge (Tyne).

Attendance: 7,500 (798 from Peterborough).