City top the table with 86, just a point ahead of Liverpool who play Cardiff later today.
The Portugal midfielder told Sky Sports: "We are so happy with the win [on Saturday] and now it's on to another tough one against Manchester United which I think will be crucial for the title.
"It's a big game for us, a big game for them. They need points to be in the top four and we need them to fight for the title.
"So we expect a very difficult game against one of the best sides in England.
"They will be motivated to beat us and we look forward to it. We know we need the win, and the pressure is on - but that's a good thing."
Read more: Alisson: no pressure on Liverpool