Former Swindon Town favourite Wayne Allison's second half header secured his latest club Chesterfield a 1-0 win over the Robins in a tight affair at Saltergate.
Allison made 120 appearances for the Wiltshire clubs in the 1990's and is still a useful striker at this level.
In a game of few chances he made on count when Sammy Clingan drilled the ball in from the right and Allison steered a header from close range just inside Swindon's right hand post.
It was enough to settle the contest which Swindon had looked in control of in the first half.
David Duke was unlucky when thumped a 20-yard shot against a post and Christian Roberts could have done better when he burst through in the 15th minute.
The striker tried to beat Carl Muggleton at his near post when Sam Parkin was in space on the edge of the six-yard box and Chesterfield scrambled the ball away.
It was different in the second half when Clingan upped the pace in midfield and forced Swindon back.
The home side might have taken the lead before Allison pounced had it not been for an excellent save from Reece Evans who dived full length to pound away a header from Ian Evatt.
Swindon's patience started to boil over when Roberts was booked for a late challenge on Evatt and Steve Blatherwick was also shown a yellow card for pushing over the Swindon striker.
Once Allison had scored, Chesterfield defence shut up shop despite Swindon forcing a number of late corners.
Both Evatt and Blatherwick missed little in the air and Allison almost set up a second goal in the closing minutes.
He played a clever one-two with sub Caleb Folan who was only denied when Evans came out quickly to block at the striker's feet.