Millwall began life after Neil Harris by ending their eight-game wait for a Sky Bet Championship victory with a 2-1 win over 10-man Leeds at The Den.
The Lions, who had first-team coach Adam Barrett in charge following Harris' decision to stand down as manager earlier this week, went in front thanks to Jed Wallace's early penalty, which saw Gaetano Berardi dismissed.
Tom Bradshaw's second goal in two games, and first goal at home for the club, then doubled the lead.
Ezgjan Alioski reduced the deficit in the first minute of the second period, but the hosts held on to record their first league victory since August and a ninth win in their last 11 home games against Leeds.
The three points sees the Lions climb up to 15th in the Championship, while Leeds drop out of the automatic promotion spots and are down to fifth.
The post-Harris era almost got off to the perfect start as Wallace exchanged passes with Mahlon Romeo, but the Lions right-back could not beat Kiko Casilla at his near post inside the first minute.
But Millwall did not have to wait long until they were in the lead. Bradshaw got on the wrong side of Berardi and the defender brought him down within 15 minutes.
Referee James Linington wasted no time in pointing to the spot and then giving Berardi his marching orders before Wallace wonderfully dispatched the resulting penalty into the top left-hand corner for his third goal in five games against the Yorkshire outfit.
The Lions continued to swarm Marcelo Bielsa's men and doubled their advantage just before the break. Ben Thompson, who was back in the starting line-up after two games, played a cheeky pass into the path of Shane Ferguson, who drilled across for Bradshaw, who in turn used the pace on the ball to apply the finishing touch with an exquisite flick into the far corner via the post.
Bielsa reacted by introducing Barry Douglas for Helder Costa at half-time, which meant Alioski moved further forward. And that change paid dividends almost immediately as Alioski tapped home Jack Harrison's 46th-minute cross from close range to score just Leeds' second goal in their last six trips to The Den.
Mateusz Klich went close to levelling for the Whites after 68 minutes, but his curling effort failed to trouble Bartosz Bialkowski in the Lions goal.
Despite being down to 10 men, Leeds applied some late pressure but Millwall stood firm to pick up a much-needed victory in front of their own fans.
What the managers said...
Millwall caretaker boss Adam Barrett: "It's been a whirlwind 24/48 hours and we wanted to put a performance on for Neil and [former assistant] David Livermore, who've been instrumental and turned the club around with an infrastructure in place Neil and David brought me in here. I'm forever thankful for that. To get a victory for him meant an awful lot.
"Leeds were second in the table so not the ideal team to play. We had a perfect atmosphere, it was a quick turnaround from Luton in midweek but the character shown was amazing. It was a good game because it was Leeds and extra added spice."
Marcelo Bielsa: "The result should be different. Each time we lose always I find few logical reasons to justify i. For me, it's always a shame to explain why we lost. I think with 10 men we were better than them. Always, we are trying to explain why what we want doesn't happen. It impacts the tolerance of the people who are listening. There were three important situations: the penalty, the red card and the next situation where Jack Harrison went down in the box.
"I prefer to analyse the game and not the referee. The second goal for them was a big impact on the match "After the first half, I decided to improve the structure and organisation in the team, but I should have taken the decision in the first half.
"Even if I didn't take those decisions in the middle of the first half, we were better with one less player, but maybe we realise more this superiority in the second rather than the first half. Maybe I could have taken this decision earlier to help the team. It's true we created few goal chances, but it's also true we had some situations that were dangerous, even if no chances were created."
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