Manchester United legend Wayne Rooney has slammed Cristiano Ronaldo for his behaviour this season and questioned why other former team-mates are defending him.

Ronaldo was left out of the United squad for a 1-1 draw against Chelsea in October after refusing to come on as a substitute in the previous game against Tottenham, where he also left the dugout before the final whistle.

The veteran forward has since returned to the side, captaining United in their most recent Premier League match at Aston Villa.

But speculation around Ronaldo's future persists after he pushed for a move away from Old Trafford ahead of the season, and Rooney warns he will be an "unwanted distraction" if he does not change his attitude.

"I don't think they're a better team with him in the side. I just think the things he has done since the start of the season are not acceptable for Manchester United," Rooney told talkSPORT.

"We've seen Roy Keane defending him, Roy wouldn't have accepted that at all. It's a distraction that Manchester United don't need at the minute, it's time to rebuild.

"Cristiano needs to get his head down and work, be ready to play when the manager needs him. If he does that, he'll be an asset. If he doesn't, I think it will be an unwanted distraction."

Ronaldo and Rooney arrived at United in consecutive years in 2003 and 2004 as two of the most exciting young players in world football.

And Rooney now wants to see United pursue a 2023 equivalent in the form of Jude Bellingham, who he was immediately impressed by when facing the Borussia Dortmund midfielder during his time at Birmingham City.

"I played against Bellingham when he was at Birmingham and I was at Derby, he actually man-marked me during that game," Rooney said. "I think he was about 16, maybe just 17, and what I really liked about him is every time I passed the ball off, he'd leave a stud in on me.

"And I remember thinking that he's got something about him, just to show the character to go out to Germany and take that league by storm.

"That mentality to perform, obviously he's been captain in quite a few of the games as well, he's going to be a huge player for England. Even though he's young, he can put some of that character into some of the rest of the squad.

"I hope Manchester United are targeting him. I hope he doesn't go to Liverpool or Manchester City. I'm sure they're doing their work, he's probably the hottest youngster in world football at the minute.

"I'm sure United are looking at that as well, I know they tried to get him a couple of years ago. He's a player that United could really do with at the moment."