Jake Cooper's early goal sent Millwall through to the Carabao Cup third round with a 1-0 victory at League One's Cambridge United.

Cooper's effort gave the Championship side the lead in the ninth minute and it proved enough for a third straight victory and a third clean sheet of the season.

Millwall dominated the opening minutes and Lyndon Dykes struck the bar before Cooper's goal but thereafter it was an even game.

Cambridge came closest to an equaliser in the second half when Glenn McConnell shot just wide from the top of the penalty area.

Millwall made 10 changes from their victory over Norwich at the weekend but started very brightly at The Abbey.

Raees Bangura-Williams drove down the left and found Dykes, who cut inside to open up space on his right boot and curled what looked like a wonderful goal, only to be denied by the bar.

Moments later Millwall hit the bar again as Luke Cundle's corner found Danny Batth but the rebound fell kindly for Cooper, the only survivor from Saturday, to shoot into the bottom corner.

Bangura-Williams then went close to adding a second for the visitors but his low shot was saved by Jake Eastwood in the Cambridge goal.

The home side grew into the game and created their first chance late in the half as Liam Bennett's header forced a save out of Max Crocombe.

After the break, McConnell should have hit the target when he was played into space on the right but his shot from 18 yards out failed to trouble Crocombe.

Shayne Lavery also went close for Cambridge when he received Bennett's cross to turn and shoot but also sent his effort wide.

The hosts continued to press in six minutes of stoppage time but couldn't send the tie to penalties.