Millwall boss Gary Rowett praised his players after their 2-1 win at Sheffield United in the Sky Bet Championship.
Jake Cooper struck a stoppage-time winner after Jed Wallace put the visitors ahead early on and Billy Sharp equalised from the penalty spot at the end of the first half.
Wallace scored in the 11th minute, when what appeared to be a cross saw the ball go over the head of goalkeeper Robin Olsen and into the net.
David McGoldrick had a great opportunity to equalise, with Bartosz Bialkowski turning the ball wide.
Sharp equalised with a penalty just before the break after John Fleck was brought down inside the area by Scott Malone.
McGoldrick then somehow put the ball over the bar from point-blank range, before the home side had Gibbs-White sent-off in the 54th minute. He received a second booking for an apparent dive after going down inside the penalty area.
In time added on, Cooper struck the winner with a superb effort from around 25 yards out.
Rowett said: “I think it’s a very difficult place to come to. Slavisa (Jokanovic) has got them playing in a very quick, incisive, bright way and we knew it would be a difficult game.
“I felt we could cause them lots of problems tactically and I think we did. I think our press was good, first half and our transitions were excellent.
“We went 1-0 up and probably should have got another goal. They made a tactical change because we were causing them those problems.
“The penalty comes and to go in at 1-1 was very disappointing after that first half an hour.
“I know if I ask Jed, he’ll say that he meant it (for the first goal)! I think he’s tried to put it in a very good area with pace.
“’Coops’ stepping up from left centre-back. It’s a brilliant strike and a fitting way for us to win the game.”
Blades boss Jokanovic said: “It’s definitely a hard defeat for us. We didn’t start the game well.
“We didn’t play a very good game. We didn’t connect and find enough power in the middle. At half time we tried to reorganise ourselves.
“We were playing better football and had some good chances, but we didn’t take the chances. I didn’t feel we were in huge danger, but they scored with a good shot.
“The referee said it was not fair play in the area (for Gibbs-White’s second booking). We were surprised Millwall did not have one (red card).
“If I talk about the referee, I don’t feel comfortable. He tried all the time not to allow physical challenges.
“I want to stay with the story of the second half and my players. They could have won this game.”