The Posh Under 21s suffered a 1-0 defeat to Fleetwood Town at the Weston Homes Stadium on Tuesday afternoon.
The Peterborough United Under 21s were beaten 1-0 by Fleetwood Town in Professional Development League action with the Cod Army moving into the top three in the table as a result.
Noah Sawkins scored the only goal of the game, beating the offside trap before creating room to shoot past Collin Andeng Ndi.
Posh had the majority of the ball and created some presentable chances with Chris Conn-Clarke heading wide at the near post and Ethan Williams glancing a header from close-range wide in the second half.
Defender Fabian Claxton made his comeback from a long-term injury as a second half substitute while several first team players got minutes under their belt with no game on Saturday.
Posh: Andeng Ndi, Freeman, Dornelly (sub Bushell 46min), Andrews (sub Claxton 60min), Weir, Christoudias (sub McWilliams-Marcano 62min), Williams (sub Simmons 72min), Conn-Clarke, Ormerod (sub Trialist 60min), Jones, Abbey. Unused subs: Mlityalwa, Al Sammour.