Substitute Tom Nicholls scored in the third minute of stoppage time as Peterborough snatched a 3-2 win at home to AFC Wimbledon in the first round of the EFL Cup.
Nicholls stabbed home the decisive goal after Marcus Maddison's right-wing corner fell into his path.
Nicholls and Paul Taylor had earlier given Posh a 2-1 lead following Chris Whelpdale's first-half header for the Dons, before another sub in Lyle Taylor looked to have sent the match to extra time.
Former Posh man Whelpdale gave Wimbledon a 35th-minute lead when he flicked on Dean Parrett's corner.
It should have been 2-0 shortly after but an unmarked Darius Charles headed Parrett's free-kick wide.
Nicholls then powerfully headed in Leo Da Silva's cross after 64 minutes, and four minutes later Paul Taylor poked in after Maddison's free-kick dropped invitingly to him inside the area.
Wimbledon's Andy Barcham sliced a shot from six yards out onto the crossbar with the goal gaping before Lyle Taylor levelled the scores with 12 minutes remaining, only for Nicholls to strike late on.