MANCHESTER -- Nemanja Matic has said he does not care if he is booed by Chelsea fans when he returns to Stamford Bridge with Manchester United on Sunday.

Matic made a £35 million summer move to Old Trafford, having won two Premier League titles, the FA Cup and the League Cup after rejoining Chelsea from Benfica in 2014.

He said he hoped supporters would "respect" his achievements but stressed that he would not be bothered by a frosty reception.

"When I played there I always gave 100 percent and we won two titles together. I'm sure they respect that, but if not I don't really care," Matic told a news conference.

"I spent a good time there, three-and-a-half years, which is a long time, and of course it's going to be something special for me to play again in that stadium.

"But now I'm on the opposite side, I have to be professional and do the best for my team. I don't have to prove to them anything. I just have to prove something to my new club."

Mourinho has said Matic was his top midfield target in the summer and the player's departure has been felt by Chelsea despite the arrival of Tiemoue Bakayoko from Monaco as a replacement, especially with N'Golo Kante injured.

Kante has missed the last six games, a spell during which Chelsea have won three, drawn one and lost two, including a 3-0 Champions League defeat at Roma.

Pundit Phil Neville said that whoever sanctioned Matic's sale should be sacked, and some United players have privately expressed surprise that the 29-year-old was allowed to move to a Premier League title rival.

Nemanja Matic makes his first return to Stamford Bridge with United. John Peters/Man Utd via Getty Images

Matic said knowing how much Mourinho had wanted him brought a "big responsibility" but declined the comment on Chelsea's transfer strategy.

"I cannot say," he said. "The only thing I can say is that I am happy to be part of this club. I'm happy to working with Mourinho. That's all I can say."

Chelsea are fourth in the table after losing two of their last four games, but United have not won at Stamford Bridge since 2012.

Matic said: "It's always important to win, especially when you're going to play big games like Sunday, so we want to take all the points.

"But we know we must respect them -- they are a good team, they're champions, and it's going to be a hard game for us, but we also have our own qualities.

"It's going to be a big game, it's difficult to say what's going to happen before it, but we will try to do our best and take points."