Ralf Rangnick praised Cristiano Ronaldo's work-rate and admitted he was surprised by Fred's match-winning strike after Manchester United beat Crystal Palace in his first game in charge.

United looked set to be held to a frustrating and goalless Premier League draw until Fred picked out the far corner of the net with a sweet right-footed strike after 77 minutes at Old Trafford on Sunday.

The Red Devils had swarmed all over the Eagles in the first half with an intense high-press approach that interim manager Rangnick will demand during his tenure.

They struggled to break down a well-drilled Palace though, until Fred came up with the only goal of the game, the 1-0 win moving United up to sixth – three points behind fourth-placed West Ham.

Manchester United 1-0 Crystal Palace

Questions have been asked over whether Ronaldo would put in the sort of shift Rangnick will expect off the ball, but the German doffed his cap to the prolific forward as he delivered his verdict on United's performance.

"I am very happy with the way the team performed, especially the first half-hour, with the pressing, it was exceptional. The only thing missing was the 1-0 or 2-0," Rangnick told the BBC's Match of the Day.

"The way we defended, we had control of the whole game, the clean sheet was the most important part. These are the things we must improve. We need to keep clean sheets. With just the one training session, I was really impressed. We did much better than expected.

"We always tried to be on the front foot. We were never not, apart from maybe the last five minutes. At all other times we were trying to keep them away from our goal.

"We wanted to play with two strikers, especially in the central position. By the way, Cristiano Ronaldo's work off the ball, chapeau."

Rangnick had to be patient for the first goal of his tenure and he raised eyebrows over Fred's decisive strike.

"I had to ask my assistant coach if that was Fred's right foot. I thought he could only shoot with his left. I'm happy for him," Rangnick said.

"It's always easier to build on things after you're successful. We must produce further clean sheets and get better at creating chances for our attack. Overall I was very pleased with the way we played today."