Manchester United interim manager Ralf Rangnick was pleased with their aggression in Monday's 1-0 FA Cup third round win over Aston Villa but said his players must put more pressure on their opponents when out of possession.
An early header by midfielder Scott McTominay put United ahead but Villa dominated large parts of the contest, striking the woodwork twice, forcing David De Gea into several saves and having two goals disallowed.
"I saw more aggression but I didn't necessarily see that much more pressing ... in order to see those pressing moments, you have to get into those pressing moments," Rangnick told United's TV channel.
"As I said, it's difficult against Villa. But what I saw was a team that desperately wanted to win and in the end, that's why we won the game."
Rangnick said he wanted United, who face Middlesbrough in the fourth round, to be tighter at the back.
"We have to develop the team into a clean sheet team ... that was another one today but still David de Gea was outstanding," Rangnick said.
"I'd have wanted him to have less saves in total, I think we had four-five shots on our goal, but again we can still improve even in that area."
United, who are seventh in the Premier League, visit Villa on Saturday and Rangnick is fully aware of what to expect.
"It will be another tough, tough game for us," he said.