Out-of-form Tranmere suffered a third consecutive defeat as they were beaten 2-1 by Northampton at Prenton Park.
The Cobblers led after less than two minutes thanks to Sam Hoskins' clinical strike but they were pegged back midway through the second half when James Norwood netted his 19th league goal of the season.
But deep in first-half injury time, Hoskins struck again and Northampton held firm after the break, meaning Rovers missed the opportunity to gain ground on the playoff pack.
Home fans were keen to see three January recruits in action but it was the visitors who took the lead early on when Hoskins outpaced Tranmere's defence before clinically stroking the ball beyond Scott Davies.
Rovers rode their luck in defence on a couple of occasions but pulled level when Connor Jennings fed Jake Caprice down the right wing and his fierce low cross was expertly turned in by Norwood.
It looked like Tranmere would kick on but Northampton had other ideas and when Hoskins speculatively looped the ball over Davies in first-half injury time it proved to be the winner.