Medy Elito's second-minute strike settled a scrappy match at Cheltenham Town 1-0 in Cambridge United's favour.
The home side almost scored in the opening minute when Carl Winchester's cross was nodded back by Jack Barthram and Danny Wright nearly turned it in, but Scott Wharton made an important intervention.
Cambridge then took the lead with their first attack - with Luke Berry's perfect cross headed in by a diving Elito at the far post.
The former Cheltenham loan player was forced off in the 29th minute with an injury.
Winchester curled an effort just wide from 20 yards after a quickly-taken corner from Liam Davis.
Cambridge looked certain to make it 2-0 in the 39th minute when Piero Mingoia's cross found Paul Lewis, but Scott Brown made an outstanding one-handed save to keep it out.
Billy Waters headed a cross from Barthram wide from a good position as Cheltenham pressed for a leveller in the second half.
A mistake from Emmanuel Onariase gave Gerry McDonagh a chance to add a second in the 73rd minute, but Brown made another good block.
Wharton cleared a looping header from Wright off the line as Shaun Derry's Cambridge held on.