Ole Gunnar Solskjaer and Harry Maguire both stepped up at the interval following Manchester United's poor first-half against Brighton.
The Red Devils went into the break 1-0 down after Danny Welbeck had given the visitors a deserved lead.
United struggled for ideas and were in need of a fresh injection, which subsequently came from their manager and the captain.
Second-half strikes from Marcus Rashford and Mason Greenwood turned the game around against a Brighton side that were well organised and made things difficult.
"Ole said his bit at half-time and so did Harry as captain," Greenwood told BT Sport.
"It was a hard night. When they scored the first goal we knew we had to react and put in a better performance. Everyone was excellent in the second half.
"I don't think we started very well but we knew we had to switch on and be focused.
"We should have started that from the moment we came out, but it's a good three points.
"There was a lot of men behind the ball and we had to have that creative spark."
Greenwood has struggled this term following an excellent debut season in the first team.
The teenager's headed winner was just his second league strike of the season, but he was pleased that his work in training had paid off.
He added: "It's a confidence booster, I've not scored as many in the Premier League.
"I scored a header tonight which is something I've been working on a lot behind the scenes."
