Posh won a penalty shootout 4-1 after the tie had finished 1-1 after 90 minutes.
The game featured a first Posh goal for Joel Randall and a dynamic substitute display from Jeando Fuchs.
Ratings Key: 10-Brilliant, 9-Outstanding, 8-Very good, 7-Good, 6-Okay, 5-Poor, 4-Very poor.
5. ROMONEY CRICHLOW
Defended steadily against a team who had plenty of possession. Struggled to find a forward pass so turned backwards a lot to keep the ball 6.5. Photo: Joe Dent/theposh.com.
6. HECTOR KYPRIANOU
A strange game with some splendid moments on the ball accompanied by losing possession in dangerous areas. His weak pass was intercepted and set Swindon in motion for their goal - 6. Photo: Joe Dent/theposh.com
7. ARCHIE COLLINS
A disappointment after a stellar display at Reading. Couldn't get on the ball and didn't keep it particularly well when he did. Substituted early in the second-half - 5. Photo: Joe Dent
8. JOEL RANDALL
It was far from a perfect display, but a first goal for the club should do wonders for his confidence. Could have scored a couple more, but encouraging he got into good positions. Teed up Clarke-Harris for a last-gasp chance to win the tie that wasn't accepted - 7. Photo: Joe Dent/theposh.com