Alex Woodyard's first goal for AFC Wimbledon gave them a 2-1 victory over 10-man Oxford that further boosted their survival hopes and severely dented the visitors' play-off dreams.
The Dons' fourth win in a row kept them five points clear of the League One relegation zone.
Nik Tzanev made good stops to deny James Henry and Sam Long, while Oxford's Jack Stevens did likewise from George Dobson's powerful effort in a goalless first half.
Oxford then broke the deadlock in the 52nd minute when Olamide Shodipo pulled the ball back for Josh Ruffels, whose placed shot found its way in.
Then came a dramatic turnaround, as Henry had a penalty - and a red card - given against him for handling on the goal line and Joe Pigott calmly rolled in his 20th goal of the season.
Two minutes later, Wimbledon grabbed what turned out to be the winner as Ollie Palmer cut the ball back for Dons skipper Woodyard, who slammed in his first-time effort.