First-half strikes from Ben Hutchinson and Sam Clucas helped Mansfield to victory against struggling Northampton.
Hutchinson put the Stags ahead with a curling 25-yard free-kick.
Clucas then scrambled a second past keeper Matt Duke after linking up well with Ryan Tafazolli.
Stags goalkeeper Alan Marriot made a string of saves, including a one-handed effort to deny Darren Carter, before Mathias Kouo-Doumbe netted an own goal past Duke.
VIEW FROM THE DRESSING ROOM
Northampton Town manager Aidy Boothroyd tells BBC Radio Northampton:
"I'm really disappointed today because we've done enough in the last two or three weeks to win plenty of games. The stats may say we were dominant but we lost a game 3-0.
"We re-double our efforts and work twice as hard. We'll be in tomorrow morning first thing, all day, and we will work every day, all day, until we get this right.
"It isn't about bringing any other players in. Losing Matt Heath isn't ideal but you've got to be able to respond.
"I've got a pretty good track record. The club is in a far better place than it was. I'm not one for resigning - I've never done that. This is my team. I believe I'm the man to put this right."