Bradford City top scorer Nahki Wells struck the only goal as the Bantams stepped up their play-off bid with victory over third-placed Northampton.
Wells hit his 19th goal of the season when on-loan Nathan Cameron failed to deal with Garry Thompson's long ball.
Cobblers goalkeeper Lee Nicholls made saves from Kyel Reid and Gary Jones, while James Hanson wasted two chances.
Ben Harding had Northampton's best effort, but his shot was superbly saved by a diving Jon McLaughlin.
Eighth-placed Bradford climbed to within two points of the play-off places - with a game in hand on seventh-placed Exeter.
VIEW FROM THE DRESSING ROOM
Cobblers manager Aidy Boothroyd tells BBC Radio Northampton:
"It's a tough place to come. They're a good side, but so are we - and both goalkeepers kept their teams in it today.
"It's a horrible mistake that has cost us but it's made by two very good, young players who are going to have very good careers at the top end.
"Thank you to our fans for supporting us again and please don't lose faith with us because we will win away from home.
"I genuinely think it's meant to be for us to go up."
Bradford City 01 McLaughlin 02 Darby 03 Meredith 05 Davies 23 McArdle 04 Ravenhill Booked 07 Reid 11 Thompson (Hines - 72' ) 18 Jones 09 Hanson 21 Wells (Atkinson - 90' ) Substitutes 12 Duke 16 McHugh 22 Nelson 14 Atkinson 24 Doyle 17 Connell 20 Hines Northampton Town 21 Nicholls 02 Johnson Booked 03 Widdowson Booked 06 Collins 12 Tozer 15 Cameron (Akinfenwa - 46' Booked ) 30 Carlisle 07 Demontagnac Booked (Robinson - 34' ) 08 Harding 11 Hackett 28 O'Donovan Substitutes 13 Snedker 04 Guttridge 22 Hornby 25 Dias 09 Platt 10 Akinfenwa 17 Robinson