Walsall took the lead on 17 minutes after first Phil Smith made a good save on the goal line, but Ricketts was there for fire in the rebound to make it 1-0.
Walsall's goal keeper was named man of the match, and he was kept busy by Swindon throughout the game.
In the second half Simon Cox had a headed goal disallowed for offside.
Towards the end of the game Swindon were pushing forward looking for an equaliser when against the run of play and in the final minute of normal time Walsall scored with a goal from Nicholas.
Within seconds of the kick off Paynter scored for Swindon with a 30 yard shot beating the Walsall 'keeper to make it 2-1.
Swindon pushed forward for a late equaliser deep into stopage time with Phil Smith coming up for a last minute corner, but Swindon ran out of time and the game finished 2-1 to Walsall.