Northampton 1-0 Cheltenham
Roy O'Donovan's goal gave Northampton a narrow lead over Cheltenham after a physical first leg of their League Two play-off semi-final.
Adebayo Akinfenwa's power in the 27th minute enabled Chris Hackett to provide the cross which O'Donovan guided home.
Cheltenham nearly levelled instantly but Paul Benson fired wide, one of three good chances he squandered.
Akinfenwa forced a superb save from Scott Brown, but the Cobblers were good value for their slim advantage.
The past 12 months have seen genuine progress for Aidy Boothoyd's side, who were 20th and only four points from relegation this time last year.
Cheltenham, on the other hand, are familiar with the post-season process having reached last season's final, only to lose to Crewe.
The Robins could be forgiven for dreading the sight of Akinfenwa, who has scored nine goals in his most last nine games against them, and he was in the mood to torment early on, out-muscling defenders and going close with two headers.
The former Gillingham man started the move for the opener, releasing Hackett who laid on the perfect ball for O'Donovan to steer home, although Brown got a hand to it on the way.
Cheltenham adjusted and Benson missed a pair of chances before Kaid Mohamed fired wide and Jermaine McGlashan stung the fingers of Lee Nicholls.
Swindon loanee Benson again failed to provide the finishing touch when nodding wide with a stooping back-post header.
Akinfenwa, benefitting from the good wing work of Chris Hackett, saw his downward header kept out by Brown as the hosts pushed for a second.
The Cobblers, who survived a late penalty scare when McGlashan and Luke Guttridge collided, have been relentless at home this season with 17 league wins.
They held out to make it 12 victories in their last 13 games at Sixfields and, more importantly, take a vital lead to Cheltenham on Sunday.
Northampton manager Aidy Boothroyd:
"I want to thank our supporters. I thought that was brilliant tonight. The crowd kept us going and I expect the same on Sunday.
"The goal was a wonderful move. It was a solid, strong, good footballing performance.
"They were frightened to death of Adebayo and you can understand why. I wouldn't want to play against him.
"He's a fantastic player and he spring-boarded most of our attacks."
Cheltenham manager Mark Yates:
"I'm probably a happier man than Aidy right now. We took a bit of a battering and didn't play anywhere near our best.
"And, although we've had to deal with a lot of balls into our box, Scott Brown has [only] had one save to make.
"We've not played near our best and we're only one down. So it is game on this Sunday."