A DISPUTED penalty proved the difference as Oxford United lost out to runaway Sky Bet League Two leaders Northampton Town.

The game's key moment came just before the hour mark, when Johnny Mullins was harshly penalised for a handball he knew little about.

Marc Richards despatched the spot kick with aplomb for the Cobblers, who had looked the more dangerous.

United struck the woodwork through Chris Maguire, but struggled to find their normal fluency on a night where they became increasingly frustrated by referee Keith Hill.

Their consolation was Accrington Stanley drawing 1-1 with Carlisle United, so the six-point cushion over the chasing pack remains.

Despite pre-match concerns over Kemar Roofe's fitness, United's top scorer was fit enough to keep his place in the side.

He was shifted out wide to accommodate the one change from Saturday's 4-2 win at Morecambe, as Alex MacDonald made way for Jordan Bowery.

United flew out of the traps and before the game was a minute old Danny Hylton forced Cobblers goalkeeper Adam Smith into a save with a header from Bowery's cross.

Although traffic problems saw many spectators miss the kick-off, the intense atmosphere in the stands matched the contest on the pitch.

Northampton worked hard to press United, prompting the hosts to adopt a more direct approach than normal.

They forged the first clear chance, on 19 minutes, when Bowery could not control Roofe's fizzed cross and shot over from close range.

But the Cobblers, who had won 12 of their last 13 league games, went on to enjoy a decent spell.

Benji Buchel saved a low shot from James Collins, who also stuck out a leg to divert a corner over the bar just before the half-hour mark.

United boss Michael Appleton will not have been happy with the number of set pieces his side gave Northampton around the box.

Late in the half one quickly-taken free-kick led to Richards guiding a header which took a superb save from Buchel to keep out.

It came amid a feisty spell before the break, where tempers boiled over several times and under-fire referee Hill dished out five bookings.

The break came at a good time to calm both sides down, but when play resumed Northampton continued to ask the questions.

Within four minutes of the restart Buchel parried a Danny Rose header and from the resulting corner John-Joe O'Toole smashed a shot against the crossbar.

The leaders were getting closer, but when they did break the deadlock ten minutes later, it came via a slice of good fortune.

Richards chased a long ball and knocked it backwards, hitting the hand of Mullins, who cannot have known much about it.

Buchel could do nothing to keep out Richards's effort from the spot, fired powerfully high into the net.

United responded well and came agonisingly close to an equaliser when Maguire's shot struck the post on 66 minutes.

Cobblers boss Chris Wilder withdrew Richards in favour of an extra man in midfield.

But United quickly carved out another opening, when Bowery's low cross found Hylton, but the forward's lay-off to Sercombe forced the midfielder to take a touch before shooting tamely wide.

United brought on Callum O'Dowda and Chey Dunkley, the latter on for skipper Jake Wright, who seemed to pick up a knock.

They huffed and puffed in the closing stages, but Smith was untroubled as Northampton closed out an eighth straight victory.

Oxford Utd (4-4-2): Buchel, Kenny, Mullins, Wright, Skarz, Roofe, Sercombe, Lundstram, Maguire, Hylton, Bowery.

Subs used: O'Dowda (Hylton 73), Dunkley (Wright 75), Ismail (Maguire 85).

Unused subs: Slocombe, Long, Ruffels, MacDonald.

Booked: Maguire, Hylton, Mullins.

Northampton Tn (4-4-2): Smith, Moloney, Diamond, McDonald, Buchanan, Holmes (Hoskins 75), O'Toole, Rose, D'Ath, Collins (Cresswell 90), Richards (Martin 67).

Unused subs: Clarke, Taylor, Adams, Prosser.

Booked: Rose, O'Toole, McDonald.

Referee: Keith Hill (Hertfordshire).

Attendance: 9,559 (1,934 visitors).