Rafael insists Manchester United must not undo the hard work that helped the Reds achieve a dramatic derby victory over City by being complacent against Sunderland.
The right-back played a big part in the team’s excellent display at the Etihad Stadium, setting up United’s second goal and winning the free-kick which Robin van Persie duly curled home in injury-time to secure a 3-2 win.
The Brazilian says confidence is understandably high in the United camp, but insists everyone is focused on maintaining the momentum with victory over the Black Cats on Saturday.
"It’s really important we get the result against Sunderland,” he told ManUtd.com. “We did a very good job last week, everyone knows that but we need to keep our momentum going if we’re going to get our title back.
"It’s been a great week in training for us – beating City was a big boost mentally for us. And the way the game went and how we won was a great feeling and the result has motivated everyone.
"When you win a big game like the derby and win it in the way we did it’s just such a good feeling. Everyone’s confidence is very high, but it’s important we don’t take our foot off the pedal and we keep things going."