OXFORD United were again left ruing missed chances as they slipped to a narrow defeat in Arctic conditions at Sixfields.

The visitors trailed to Ben Harding's goal in first-half stoppage time, but went on to control the majority of the second half.

But just as in their defeat to Chesterfield a week earlier they were unable to turn pressure into a breakthrough as Cobblers goalkeeper Lee Nicholls made several smart saves.

It meant a missed opportunity to make up ground on the sides not in action, leaving their play-off hopes hanging by a thread with six games remaining.

Tom Craddock replaced Deane Smalley in the only change from the side which started United's 1-0 defeat to the Spireites a week earlier.

Northampton had won their previous eight home games and came flying out of the traps.

Just 35 seconds were on the clock when a quick throw caught the visitors napping, leading to a chance which Harding fired over.

The Cobblers adapted to the awful conditions, which saw snow swirl around the ground in freezing temperatures all afternoon, quicker than United and quickly stamped their authority in the game.

Chris Hackett and Ishmel Demontagnac were threats out wide, getting the better of the United full backs in the opening 20 minutes.

Clarke Carlisle headed a good chance over on nine minutes as the U's battled to keep on level terms.

An even better opening fell to Cobblers' top scorer Adebayo Akinfenwa in the 17th minute, but he could only head Hackett's cross straight at Luke McCormick.

United gradually gained a foothold in the game, with Sean Rigg their main outlet.

It took them 37 minutes to carve out a clear chance, when the front two combined to slice through Town's rearguard.

James Constable played in Craddock, who fired in a low shot left-footed which Nicholls saved.

The U's were on top and only an excellent challenge from Joe Widdowson prevented Alfie Potter from tapping in Rigg's low cross.

But in stoppage time the visitors were hit by a sucker punch.

Hackett got the better of Liam Davis and hung up a cross which McCormick could only punch straight to Harding.

The midfielder kept his cool in a crowded penalty area and picked out the top corner of the net.

United were unhappy with the timing of the goal, which came well past the two minutes of stoppage time which had been signalled by the officials. They also felt Andy Whing had been fouled in the build-up, but the referee waved away the protests.

The snow began to settle during the interval and an orange ball was needed in the second half.

Constable had a low shot saved by Nicholls, before Northampton carved out a superb chance to double their lead.

Harding was given space to run forward and he picked out Clive Platt with a chipped cross.

The striker nodded down perfectly for Akinfenwa, who somehow missed his kick with the goal gaping.

But with only a goal in it United were always in the game and they had a good spell just after the hour mark.

A low cross from Davis picked out Whing, but he could only scuff the shot to Nicholls.

Deane Smalley came off the bench and was quickly in the action, flicking a whipped free-kick from Davis just over.

Northampton were pinned back for the best part of 20 minutes, as United poured forward in search of an equaliser.

Michael Raynes headed a Davies cross into Constable's path, but a combination of Carlisle and Nicholls blocked his shot.

Their clearest chance came in stoppage time when Constable found some space in the box.

His left-footed shot was superbly kept out by the goalkeeper and the ball fell to a Town defender, who cleared.

The game grew increasingly bad tempered as time wore on, with five players booked.

Raynes sparked a shoving match involving most of the 22 players for a late tackle on Demontagnac.

It was the final incident of the game, which left United reflecting on a familiar fault - a lack of quality in front of goal - which again proved costly.

Oxford Utd: McCormick, Batt, Raynes, Wright, Davis, Potter, Whing, Davies, Rigg (Smalley 63), Craddock, Constable.

Unused subs: Brown, Heslop, Worley, Duberry, O'Brien, Parker.

Northampton: Nicholls, Johnson (Guttridge 71), Langmead (Collins 12), Carlisle, Widdowson, Hackett (Robinson 83), Tozer, Harding, Demontagnac, Akinfenwa, Platt.

Unused subs: Snedker, Hornby, Dias, O'Donovan.

Referee: David Webb.

Attendance: 6,151 (1,176 visitors).