Wayne Rooney has told Romelu Lukaku that he cannot afford to drop his performance level if he is to make a success of himself at Manchester United.

Lukaku completed a move to Old Trafford from Everton last weekend, joining the Red Devils for a fee that could potentially reach nine figures when add-ons are included.

Rooney headed in the opposite direction, meanwhile, returning to the club that he left 13 years ago after breaking onto the scene in impressive fashion.

The England international has offered a word of advice to his former club's latest big-name signing, while also claiming that the dressing room now lacks the leaders of old following the departures of academy graduates Ryan Giggs, Gary Neville and Paul Scholes in recent years.

"There are standards that you have to keep when you are at Manchester United," he told reporters. "That came from the ­manager Sir Alex Ferguson when I went to United and it was then passed down through the dressing room by the likes of Giggsy, Gary Neville and Scholesy.

"Over the last few years, it was down to me and Michael Carrick to keep the new players maintaining those ­standards. That became more difficult over the last few years, with some of the ­players who joined the club.

"There are ­traditions at United that have to be maintained. It's become harder, but that's not my problem anymore. I'm just ecstatic to be back at Everton."

Rooney marked his return to boyhood club Everton with a long-range strike in the pre-season friendly win against Gor Mahia on Thursday afternoon.