MK Dons were beaten 2-0 by Peterborough at the ABAX Stadium, courtesy of two goals in the opening eight minutes of the second half.
After a tight first half, the home side took the lead when defender Ryan Tafazoli headed into the back of the net at a corner. MK Dons had appealed for a foul against their goalkeeper, but appeals were waved away.
Moments after Ricky Miller had a goal disallowed, Peterborough then had a second when Marcus Maddison intercepted possession before advancing and then placing a strike beyond Nicholls.
The best chances before half-time had seen Lee Nicholls make two firm stops to deny Gwion Edwards, while at the other end, Aaron Tshibola and Alex Gilbey saw efforts spin wide.
Following Peterborough’s fast start to the second half, the home side had further chances, with Jack Marriott seeing two efforts go wide, and a second pair of shots denied by Nicholls.
The Dons made a triple substitution and had a handful of chances. Robbie Muirhead saw one effort denied by home goalkeeper Jonathan Bond, while the goalkeeper also denied Scott Wootton. But the visitors were unable to prevent their first league defeat in September, and will now look to bounce back on Saturday when they host Rochdale.