Two goals from Kwesi Appiah set the tone as Cambridge United came from behind to beat rivals Oxford United 5-1 in their Sky Bet League Two clash at the Abbey Stadium.
The visitors took the lead in the ninth minute when U's keeper Chris Dunn failed to keep out Danny Hylton's header following Tom Newey's left-wing cross.
But Cambridge were soon on the front foot and Oxford were indebted to a fine save from keeper Ryan Clarke, who tipped a 25-yard drive from Appiah on to the crossbar.
However, Appiah was not to be denied for long and he was celebrating an equaliser in the 41st minute when he fired an angled volley past Clarke from the right side of the area.
And the player doubled his money on the stroke of half-time, lofting the ball home from another difficult position at the second time of asking, after Clarke had initially pulled off a good close-range save.
Cambridge doubled their lead in the 54th minute when Appiah showed good vision to pull the ball back for Ryan Donaldson who kept his composure and finished smartly.
Tom Elliott then scored his fifth league goal of the season, his fine header giving Clarke no chance following Greg Taylor's cross.
Oxford's best chance came at 2-1 when Michael Raynes hit the post from close range, while only good saves from Clarke prevented Harrison Dunk and Liam Hughes adding to the score. He was helpless to prevent Robbie Simpson adding a fifth for Cambridge from Donaldson's corner a minute from time.