Ole Gunnar Solskjaer said he and his Manchester United players weren't satisfied with their performance despite a 1-0 win at Leicester on Sunday.
United returned to winning ways following their draw at home to Burnley in midweek, but they were far from convincing after Marcus Rashford scored what proved to be the only goal nine minutes into the game.
Solskjaer told Sky Sports: "We didn't play particularly well, we could have slowed it down in the second half but we defended well. Eric [Bailly] and Victor [Lindelof] were fantastic, and David de Gea.
"We put our bodies on the line, there were a couple of bruised noses, knees and dead legs but we fought for the three points.
"A clean sheet is always a foundation to build on and will give the lads confidence. They're not 100 per cent happy with the performance, because we know we can do better.
"It's a hard place to come, the first goal is vital against a team like this and I thought we started brilliantly. Marcus had a great chance from Luke Shaw's cross and finished the ball fantastically well when Paul [Pogba] played him through. The start laid the foundations."
Alexis Sanchez was given a first league start since Solskjaer's arrival at United but had little influence on the game before he was withdrawn for Anthony Martial after half-time.
But Solskjaer defended the Chilean's performance, saying: "He did well, we had to change the game. He's sharp, he worked well defensively - we never created chances for him but he's improving all the time."