Harvey Knibbs struck a controversial late winner as Cambridge beat Exeter 2-1 to reach the FA Cup third round for the first time in five years.

Knibbs headed in Wes Hoolahan’s cross two minutes from the end but saw it disallowed for offside, only for the goal to then be awarded following Cambridge protestations.

The visitors had earlier gone ahead when Jubril Okedina clipped Sam Nombe in the box, with Nombe scoring from the penalty spot after 10 minutes.

Cambridge were level 13 minutes later following good work by James Brophy, and his pull-back was despatched by Adam May.

Three minutes before the break Exeter’s Jevani Brown laid the ball off to Archie Collins, whose effort came off the inside of the post.

Cambridge substitute Sam Smith fired a great chance wide 10 minutes from time, then Conor Masterson rattled the post for the hosts before Knibbs, another late replacement, headed the winner.

With Exeter pressing for an equaliser, Cambridge broke and Jensen Weir was felled, only for Joe Ironside’s penalty to be pushed away by Cameron Dawson nine minutes into stoppage time.