Substitute James Spencer's stoppage-time equaliser earned Cambridge a point at League Two leaders Northampton.
John Marquis looked to have grabbed the winner for the Cobblers with his 71st minute goal, only for Spencer's strike late.
Ben Williamson was off target for Cambridge early on before the home side twice went close.
Zander Diamond had an effort blocked and James Collins fired wide of the upright.Brendan Moloney and Marquis went close as Cobblers looked for the breakthrough.
Josh Coulson was just off target with a decent header for the visitors.Both goalkeepers were called into action just before the break, Zeli Ismail was denied by Adam Smith who also thwarted Ryan Ledson.
Lee Martin's low drive was well saved by Will Norris while John-Joe O'Toole shot wide on the stroke of half-time.
After the restart Norris did well to keep out a header from Collins who then had a low drive saved by the Cambridge keeper.
Collins looked the man most likely to make the breakthrough but it was Marquis who broke the deadlock in the 71st minute when he headed home following a corner from Joel Byrom.
.Ledson was off target and Spencer headed over, while Collins went close again when he headed wide before substitute Lawson D'Ath fired just off-target from the edge of the box.
Smith saved a header from Leon Legge before keeping out Luke Berry's drive from the edge of the box.
But he could not do anything about Spencer's strike which found the top corner in the first minute of stoppage-time.
Source : PA