Cambridge were the first winners in this season’s Carabao Cup following a 1-0 victory over 10-man Millwall.

Liam O’Neil’s fine low finish from the edge of the box in the 59th minute proved decisive as the Sky Bet League One side knocked Championship opposition out of the competition for the third time in four years.

Millwall’s George Honeyman was sent off for a second yellow card two minutes after the goal, but the Lions still had chances to take the tie to penalties.

Substitute Isaac Olaofe ran onto a defensive mistake but was well denied by goalkeeper Will Mannion, before also heading a free-kick onto the top of the crossbar.

Before O’Neil’s goal, Olaofe had broken clear and fired into the side-netting, and a big chance after 54 minutes ended with Cambridge defender Greg Taylor making a vital flick to head Murray Wallace’s effort over.

All the key activity came in the second half, with headers off target for Millwall’s Ryan Leonard and Shaun Hutchinson following corners the only notable openings before the break.

It was left to O’Neil to hit the winner as Cambridge gained a measure of revenge for being beaten by the same opponent in the second round last season.