Jonny Evans is expecting a rough ride from Norwich strikers Grant Holt and Steve Morison on Sunday.
The bruising centre-forwards have caused a lot of problems for opposing defenders this term and Evans is steeled for a physical challenge at Carrow Road in a match United need to win to keep the heat on Manchester City at the top of the table.
Following the tricky assignment at Carrow Road, the Reds are at third-placed Tottenham and, with City at home in their next two fixtures, it's vital Sir Alex's side keep in contention.
"Norwich have done well since they got promoted," said Evans. "It seems like a pretty tough place to go. They have two big lads up front who seem to make it hard for you.
"I think Holt has played in every league. He is a big strong boy, as is Morison. It is going to be a real battle, a lot different to Ajax. In the Premier League, you are used to challenges, when it is a bit more rough. Ajax was a lot different to what we are expecting at Norwich. That is what it is all about.
"Paul Lambert seems to have them working really hard. It is going to be a tough game. It is a game their fans and players will have been looking forward to all season.
"These next two games are massive. Every week, we seem to be saying it but we are away from home and have an international in between, which is not great preparation. But Spurs will have a lot of players away as well, so it depends on who recuperates better that will get the result."