Man United on alert as Real Madrid prepare to SELL Cristiano Ronaldo

Spanish newspaper Sport claim the Portugal star will be sold either this summer or next with Madrid president Florentino Perez hoping to cash in on him before his re-sell value drops.

Ronaldo joined Madrid in 2009 from Manchester United for an at the time world record fee of £80m and has a contract until 2018.

And despite turning 30 at the start of last month he's scored 30 goals in 22 Liga appearances so far this season and has won back-to-back Ballon d'Or awards.

However, according to the reports, Perez believes he is already passed his best and remains concerned about the damage his chronic knee injury will do long-term.

Ronaldo also came in for criticism following his birthday celebrations after the defeat to Atletico Madrid.

Perez has also earmarked Gareth Bale as his long-term successor and wants the Wales winger to take centre stage eventually.

Ronaldo has constantly flirted with a return to Manchester and David Moyes was keen on bringing him back to Old Trafford when he was in charge.

Louis van Gaal admitted earlier this season the club was capable of breaking the club's transfer record, having spent £59m on Angel Di Maria last year, but that was in relation to reports of Bale coming back to the Premier League.

United however have maintained a good relationship with Ronaldo and the player has made a point of being respectful towards fans whenever playing against them.

Last month, his agent Jorge Mendes admitted Ronaldo "loves Manchester United fans" but said he would not be leaving Madrid.

"He loves the Man United supporters, he told me because he was there for six years," Mendes told the BBC.

"But now he is at Real Madrid, he will not leave Real Madrid.

"Cristiano Ronaldo is the best player ever in the world and the best sportsman ever.

"So you can't compare Cristiano Ronaldo with anyone else. It's impossible to find someone like him."

Mendes also recently insisted Ronaldo is keen to continue playing late into his thirties, however if Madrid are keen to cash in on him he may have to seriously look at the option of making a Premier League return.