The defensive duo, who between them amassed more than 750 appearances for the club in all competitions, both signed four-year deals with the Black Cats on Thursday, linking up with former United defender Steve Bruce at the Stadium of Light.
And Nani has paid tribute to the pair, particulaly Brown, who he admitted played a key part in his career immediately following his arrival from Sporting Lisbon in 2007.
"I think Wes has had a brilliant career in United," he told MUTV. "He was a very important player for United and is a fantastic professional and a good friend.
"He helped the young lads a lot and was always ready to play with the team-mates. He's a very friendly player and was very close to me as well. I enjoyed my time I played with him.
"I've enjoyed playing with a lot of players and these two players were very good for me as well because of the experience they've got.
"They are very good people and I hope they do well and keep doing their best at Sunderland."
And the 24-year-old, who has scored 16 times in 95 league games for the Red Devils, said he has no doubt that Brown will not think twice about kicking him when the two sides meet each other in 2011/12.
"100 percent! He kicked me of course in training. This is the way he played and why he's been a fantastic player."
‘He instantly popped into our ratings as one of the best U21 midfielders in Europe. The impressive thing is Slot has made him into more of a no.6' Inside Ryan Gravenberch's transformation at Liverpool
‘I don’t think Liverpool would look at Ollie Watkins, a striker isn’t a pressing issue for them – it’s Arsenal who need one’ Former Reds star explains why his old club don’t need an out-and-out forward this summer
