Mark Sykes' 61st-minute winner helped in-form Oxford beat AFC Wimbledon 2-1 to move second in Sky Bet League One.
Shane McLoughlin's first-half own goal had given Oxford the lead, but it was cancelled out by Joe Pigott's equaliser just after the restart.
The result meant Oxford ended the hosts' unbeaten home run which had dated back to September 21.
Wimbledon started brightly and Pigott had a goal ruled out for offside in the 16th minute.
Oxford took the lead 10 minutes later when Sam Long's cross hit Wimbledon midfielder McLoughlin and found the net.
Pigott got his goal a minute after the restart when he volleyed Luke O'Neill's cross home.
But in the 61st minute the visitors regained the lead when Sykes made a sublime run before slotting home when one-on-one with Wimbledon goalkeeper Nathan Trott.
Oxford then had a goal disallowed after the referee decided Trott was pushed over his own line.