Adam May scored an extra time winner as Sutton shrugged off the disappointment of conceding a penalty in injury time of normal time after leading 2-0.
Craig McAllister and Dean Beckwith scored either side of half time to put U's in control, but ex Sutton player Sam Rents pulled one back before Lloyd Dawes levelled from the spot in the third minute of stoppage time after a foul by Dan Fitchett. May's low shot from twenty yards restored an advantage that U's this time kept to earn a home tie against Boreham Wood on 4th February.
On the down side, Beckwith suffered a hamstring injury which threatens to rule him out of Sunday's game against Leeds.
[arve url="http://www.youtube.com/watch?v=OlDD6rWaUU4"/]