Leaders Leyton Orient were beaten for just the third time this season when going down 1-0 to promotion chasing Northampton at Sixfields.
Ben Fox scored the game’s only goal early in the second half as the Cobblers bounced back to winning ways, opening up a seven-point cushion over fourth in the process.
Orient edged a cagey first half and they had the better moments in front of goal as Idris El Mizouni and Jordan Brown missed the target from long-range.
Darren Pratley brought a decent save out of Lee Burge after trying to convert Theo Archibald’s superb pass, but that was about it for chances before the break.
Neither side were helped by injuries with three players forced off in the first half, but Northampton broke the deadlock just five minutes into the second period when Fox squeezed a shot into the bottom corner after Lawrence Vigouroux had brilliantly kept out Sam Hoskins following a slick counter-attack.
Omar Beckles had an equaliser disallowed for offside after a long consultation between linesman and referee on the hour mark, but the visitors created very little else before Beckles saw red for an elbow in stoppage-time.
