Barry Corr scored in stoppage time to secure Cambridge an enthralling 3-2 win against Notts County.
Seconds after Kane Hemmings missed a glorious chance to win the game for the visitors, substitute Corr nodded George Maris' corner in off the underside of the bar to secure victory for the U's.
Notts County led at half-time courtesy of Enzio Boldewijn's sensational strike from distance after he ran inside and thundered an effort into the top corner, only for Ade Azeez's brace to turn the game on its head.
Having not scored for the club all last season, Azeez equalised seconds into the second half when Shaun Brisley and Ross Fitzsimons left Harry Darling's long clearance for one another and he stole in to guide the ball home.
Just after the hour Azeez was slipped through on the right and saw his initial shot blocked before powering the rebound beyond Fitzsimons.
Richard Duffy headed a corner in from close range to equalise for the visitors 12 minutes from the end before the grandstand finale.