Trai Hume scored the only goal of the game as promotion-chasing Sunderland claimed a 1-0 win over Millwall.
Following a positive start from the hosts at the Stadium of Light, the full-back fired the Black Cats ahead in the 20th minute with a fantastic volley stemming from a well-worked corner routine.
They had chances to extend their lead through Wilson Isidor and Jobe Bellingham and although Luke O'Nien had a penalty saved late in the game, Hume's goal proved to be enough as Sunderland strengthened their grip on fourth place in the Championship.
Millwall forced some routine saves from Sunderland goalkeeper Anthony Patterson and their best effort came through Josh Coburn's header after the break, but defeat is a dent in their bid to reach the play-offs, as they remain six points outside the top six.
Sunderland were quickly out of the blocks and soon created an excellent opportunity when Chris Rigg played a through ball into Isidor on the right, and Millwall keeper Lukas Jensen needed to be alert to claw his shot away.
The rebound fell into the path of Bellingham, who saw his tame attempt blocked, before Jensen was called into action again to save Rigg's effort.
Patrick Roberts' curling strike was deflected behind as Sunderland continued to push, and their impressive start was rewarded in the 20th minute.
Roberts launched a pinpoint cross into Hume on the left and he smashed home a first-time strike into the bottom corner.
Former Black Cat Aaron Connolly sent a free-kick from outside the box over the crossbar as Millwall looked to respond and an acrobatic effort from Japhet Tanganga was easily held by Patterson.
The Sunderland goalkeeper made some comfortable saves to keep his side on top, catching a teasing cross from Billy Mitchell before pouncing on a low Luke Cundle shot.
Following a scrappy start to the second half, the hosts suddenly sprung into action when Bellingham had an effort blocked and Jensen made a great stop to tip Isidor's powerful header from close range over the bar.
The game was then stopped for around five minutes due to an incident in the crowd which saw Sunderland's medical team called over from the bench to attend.
When play resumed, Sunderland had a penalty claim waved away after Dan Neil went down in the box and Bellingham saw another powerful strike cleared away.
Millwall then threatened as Tristan Crama crossed into Coburn, but the forward headed straight at Patterson.
Sunderland began to push and Romaine Mundle's shot was blocked following an intricate move on the edge of the box before Hume blasted narrowly over the bar from distance.
The hosts were awarded a penalty in the final 10 minutes when Mundle was brought down in the box, but O'Nien's low spot-kick was easily palmed away by Jensen as the outcome of the match remained in the balance.
Millwall searched for a late equaliser, but substitute Mihailo Ivanovic's low attempt was blocked in stoppage time as Sunderland held on for the points.
The managers
Sunderland's Regis Le Bris:
"It's a new chapter, we cannot waste time. It's important to build this momentum and be accurate, precise for every single minute we play now because the end of the season will be tough.
"The games we play will be very tight, every detail counts and we need to build this momentum now to be ready for the end of the season.
"After the defeat at Coventry we could've struggled a bit more. When the confidence is dropping very deep, sometimes it's difficult to react and to restart the team.
"This step was important and so far we've always showed good reaction after defeats. For the end of the season, I think the players, the club we are really connected with the goal we want to achieve.
"It would be difficult for automatic promotion. So for us the only solution is through the play-offs and we know the semi-finals will be very tight.
"Every detail counts and we have to build these details now and don't have to waste time."
Millwall's Alex Neil:
"They played like a 4-4-2 block at times, playing through that's not easy.
"You probably need to work around it and play more crosses in the box, that's where our chances came from in the second half. I just didn't think we were as progressive with our passing as we can be.
"I thought it was a reasonable performance for the team, I wasn't displeased with the performance, I was probably more displeased in the manner in which we lost the game, which was a set-play."
