Peterborough caused the first shock of the Carling Cup as they beat Southampton 2-1 to progress to the next round.
Southampton, fresh from a 4-1 home defeat to Crystal Palace at the weekend, again looked vulnerable at the back as Peterborough came out all guns blazing.
The home side took the lead with an own goal in the 21st minute as Grzegorz Rasiak inadvertently headed Dean Keates' corner past nervy goalkeeper Bartosz Bialkowski.
Rudolf Skacel struck the post for Southampton moments later but Peterborough remained in control and doubled their advantage after 26 minutes as Bialkowski saved from Keates and George Boyd tucked away the rebound.
Rasiak pulled a goal back for Southampton in the 37th minute, tapping home at the back post after a delightful run and cross from the lively Nathan Dyer.
Bradley Wright-Phillips missed a superb opportunity to equalise just before half-time but the chances kept coming after the break.
Aaron McLean hit the crossbar from another pinpoint corner from Keates, before Skacel drew a fine save from Shwan Jalal at the other end.
As the clock ticked down towards 90 minutes Southampton started to pen Peterborough back into their own half, but to no avail.