Wayne Rooney feels Cristiano Ronaldo has adapted his game to the extent that the Portuguese superstar can play on until he is 40.
Ronaldo, 36, is one day away from kicking off his second stint at Manchester United, after sealing a return to Old Trafford from Juventus on the final day of the transfer window.
Expectation has been building on the back of an international break, but Ronaldo has been training with the team and expected to feature against Newcastle on Saturday.
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Rooney will be an interested spectator, provided he can secure a ticket at Old Trafford, and is expecting big things from his former team-mate.
"The last time he played here, he was more of a runner, a great dribbler, with pace and power," Rooney, who is now manager of Derby County, said.
"Whereas now, he's a goalscorer. I think his game has adapted dramatically.
"His ability is obviously one thing, but then he's also looked after himself massively. He's still in great condition. It wouldn't surprise me if he's playing until he's 40, like Ryan Giggs did, and still scoring goals.”
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Rooney feels the United players will have to adapt to having Ronaldo in the team, but believes his guarantee of goals will help the process.
"His team-mates will have to work a little harder,” Rooney said. “But if it's anything like last time - towards the last two years of playing with him - the team allowed him to do that because he scores you goals, and goals win you games."
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