Cambridge United have progressed in the Carabao Cup with a 1-0 first-round victory over Millwall at the Abbey Stadium.
Liam O'Neil struck in the 59th minute to put the hosts in front before George Honeyman was sent off for the Lions.
Cambridge got revenge for a 3-1 defeat to Millwall in the second round of this same competition last year as they advanced past the first round for the fourth year in a row.
Story of the match
Cambridge manager Mark Bonner made nine changes to the side that defeated MK Dons in their League One season opener as only George Williams and Joe Ironside kept their places.
Gary Rowett opted to make five changes to his starting XI following a 2-0 victory over Stoke City in their EFL Championship opener with Charlie Cresswell, Murray Wallace, Ryan Leonard, Tom Bradshaw and Honeyman retaining their spots.
The visitors were forced into a substitution just minutes into the game as Bradshaw suffered an injury on the first attack of the game, replaced by Isaac Olaofe.
Olaofe was straight into the action, his pull-back finding Mason Bennett, but his shot from the left wing was blocked and cleared by Greg Taylor.
On 14 minutes, George Saville won the ball in the middle of the park, took one touch and tried his luck, but he went wide of the Cambridge goal.
Saville then sent in a corner kick that was met by Ryan Leonard, but he could only send his header wide after getting into the penalty area.
Bennett was at the heart of the next Lions attack, his cross scrambled away by the U's defense before it could reach the onrushing Danny McNamara.
The hosts carved out their first real chance in the 25th minute, Seikou Janneh heading a driven cross towards Shilow Tracey with Shaun Hutchinson and George Long combining to see off the danger.
Tracey then drilled one later on, his cross denied by Leonard, who saw off the danger to prevent Ironside from doing any damage.
Hutchinson was then on hand to meet a Saville corner with his head in the 33rd minute, but he nodded wide. Five minutes later, Brandon Haunstrup shot from 25 yards, but failed to test Long's goal.
Halftime: Cambridge United 0-0 Millwall
Olaofe had the initial chance of the second half, racing down the left and after storming into the box, could only find the side netting with his attempt.
Tracey then beat the Millwall defense, but the tandem of Hutchinson and Cresswell were on hand to guide the ball to safety. Moments later, Lewis Simper went high and wide from a corner.
On 53 minutes, the visitors nearly opened the scoring, the ball breaking to Wallace, his right-footed effort deflected off of Taylor under the Cambridge crossbar.
Six minutes later, the U's found the goal they were looking for. The outstanding Tracey started the passage of play with Jack Lankester eventually squaring to O'Neil, who beat Long into the bottom corner.
A minute later, Honeyman was shown his second yellow card for an unnecessary challenge, reducing Millwall to ten men.
Despite being down a man, Olaofe had a golden chance to level the match, released in a one-on-one position, but Cambridge goalkeeper Will Mannion denied him.
Two minutes later, the Londoner came close again, heading against the crossbar. A Hutchinson knockdown from a corner found Olaofe, but he went over.
In the waning minutes of the match, James Brophy raced down the left and set up Sam Smith, who went wide of the crossbar from 12 yards out.
That was the last action of the game on a night that saw the U's defense remain resolute to move into round two.
Player of the match
Tracey was causing Millwall problems for the entirety of the match. He showed the ability to start the Cambridge attack, particularly in the passage of play that led to O'Neil's goal.
He also showed his quickness, beating the Millwall defense and taking a couple of shots himself. Overall, a superb performance.