Posh beaten 2-1 by Birmingham City as the Blues clinch automatic promotion back to the Sky Bet Championship.
Peterborough United suffered a narrow 2-1 defeat to Birmingham City at the Weston Homes Stadium on Tuesday evening as the Blues secured automatic promotion back to the Sky Bet Championship following first half goals from Alfie May and Taylor Gardner-Hickman.
Darren Ferguson's men put in a much improved showing from the weekend defeat to local rivals Northampton Town, but couldn't force an equaliser despite causing one or two problems from set-pieces.
A side showing six changes from the weekend, including Nick Bilokapic who replaced Jed Steer between the sticks with the former Aston Villa man suffering with a knock, competed well against the Blues, who celebrated at the final whistle as they secured an instant return to the Championship.
Bilokapic made a smart early stop with his legs to keep out May on two minutes after a poor back pass before MAY opened the scoring with a close-range header, which found the back of the net via the underside of the crossbar.
Abraham Odoh saw a shot blocked before Posh levelled through POKU who lashed home a left-footed effort from inside the box after a corner was only half cleared.
Malik Mothersille fired wide after rounding the goalkeeper, it was a tight angle for the former Chelsea man and he couldn't wrap his foot around the ball.
Birmingham got their noses in front once more as GARDNER-HICKMAN saw a low angled drive find the back of the net with Bilokapic unable to keep it out.
In the second half, Posh caused one or two issues with Sam Hughes seeing a header at the back post from a Mills corner kept out by Allsop.
At the other end, Jay Stansfield fired wide after coming off the substitutes bench while Luke Harris fired over from the edge of the box.
At the final whistle, the Blues players were able to celebrate with their supporters, with over 3,700 in attendance. The two sides meet again at Wembley Stadium on Sunday afternoon.
Posh: Bilokapic, Johnston (sub Dornelly 62min), Collins (sub De Havilland 84min), Mothersille (sub Hayes 62min), Odoh, Poku, Jones (sub Lindgren 75min), Susoho (sub Kyprianou 62min), Hughes, Mills, Fernandez. Unused subs: Blackmore, Katongo.
Birmingham City: Allsop, Klarer, Bielik, May (sub Stansfield 75min), Leonard (sub Seung-Ho 62min), Willumsson, Gardner-Hickman (sub Anderson 62min), Cochrane, Sampsted (sub Laird 62min), Iwata, Harris (sub Hanley 87min). Unused subs: Peacock-Farrell, Dowell.
Half-time: Peterborough United 1-2 Birmingham City
Full-time: Peterborough United 1-2 Birmingham City
Attendance: 10,640 (3,739 Birmingham City fans)
Referee: Ben Toner