Cambridge are still looking for a first league win of the season after a 2-1 defeat at Mansfield.
Emmanuel Longelo gave United hope after cancelling out Lee Gregory’s opener just after half-time.
But Gregory gave Mansfield a first home win of the campaign with a brilliant curling finish midway through the second half.
Josh Stokes saw a shot comfortably saved by Christy Pym during a cagey opening 15 minutes.
Gregory put Mansfield ahead on 39 minutes after a fast interchange involving Will Evans and Elliot Hewitt created an opening.
But Longelo levelled with a thumping finish five minutes after the restart following a brilliant counter-attack.
The visitors saw a strong penalty shout waved away after Shayne Lavery went down following a challenge by Deji Oshilaja on 65 minutes.
Mansfield found the winner three minutes later when Gregory curled home a beauty from just inside the box.
Pym saved brilliantly to block from Dan Nlundulu deep in stoppage-time before Aaron Lewis brilliantly cleared off the line from Sullay Kaikai with the last kick of the game.
