Andy Clarke's 16th goal of the season proved enough for Peterborough to claim victory over 10-man Northampton.

The Posh striker capitalised on a 55th-minute error from goalkeeper Nathan Abbey, who rushed out of his area and collided with defender Paul Reid, to roll the ball into an empty net.

In a tense derby atmosphere, the Cobblers were reduced to 10 men after striker Darryn Stamp was sent off in the 70th minute for a second bookable offence.

Moments earlier, Stamp had been denied an equaliser when goalkeeper Lee Harrison saved bravely at his feet.

Derek Asamoah should have put Town in front midway through the first half, but he failed to hit the target with the goal at his mercy.

Harrison preserved Peterborough's advantage late on when he punched away a fierce volley from Paul McGregor, to leave Northampton with just one win in nine league games.

Northampton: Abbey, Gill, Hope, Reid, Carruthers, Rahim, Harsley, McGregor, Stamp, Gabbiadini, Asamoah. Subs: Marsh, Sampson, Burgess, Thompson, Turner.

Peterborough: Harrison, Arber, Rea, Burton, Gill, Bullard, Jelleyman, Shields, Hendon, Andy Clarke, Fenn. Subs: Farrell, Scott, Newton, Danielsson, Semple.

Referee: J P Robinson (E Yorkshire).