"They were not important, they were crucial. I told the players that at half-time," Mourinho said of the three points.

"I don't think, if we didn't win this match, we could still think about chances (of Europe). (It) was three points or nothing. Three points was fundamental."

The clean sheet was just their fifth in the Premier League all season and they looked far more solid than prior to lockdown, which Mourinho says is the result of some hard work.

"We worked hard and we started that when we were only allowed to work in groups of five," he said. "We chose always the back four to be together and we worked a lot on that.

"In the past two weeks we did it collectively and I am really happy that in the last two matches we have only conceded one goal from a funny penalty and we managed to be really solid. I am happy with that."

West Ham's second loss from two games since the restart saw their relegation fears deepen.

They had genuine grievance with Soucek's own goal, not ruled out for a handball in the build-up, while they could have drawn level at 1-1 but Jarrod Bowen's effort hit a post.

Bowen was West Ham's brightest player and rued his late miss.

"On another day it goes inside the post, and if that goes in it's 1-1 and we're right back in the game," he told the club's official website.

"Unfortunately it's hit the post and gone wide.

"The first goal, being an own goal, was tough to take, but I felt we were still in the game. We had a couple of chances, we hit the post but they caught us on the counter-attack to knock the stuffing out of us with the second goal so late on.

"I don't think you can fault any of the boys' effort – you could see that we worked hard without the ball, it's just unfortunate that the manner of the first goal killed us a bit."