Manchester United Transfer News: Cristiano Ronaldo, Rafa Benitez Rumours Grow

Cristiano Ronaldo is reportedly "sick" of working under Real Madrid manager Rafael Benitez, which could be a big boost to Manchester United's hopes of seeing the Portuguese superstar return to Old Trafford.

Recent reports have suggested that Ronaldo may be primed to exit the Bernabeu come the end of the season, with former Los Blancos president Ramon Calderon recently suggesting as much, per French outlet Le Parisien (h/t Sam Marsden on Goal).

El Chiringuito TV (via Marc Williams in the Daily Star) has now added fuel to the fire by reporting that the 30-year-old is "sick of the blunders of Rafa Benitez."

This is not the first time that reports have emerged of a strained relationship between Benitez and his star player.

Ronaldo has previously been reported to be unhappy with Benitez's meticulous training methods, per El Confidencial (h/t Sport).

According to the Mirror, the Red Devils have consistently been linked with making a move for their former star over the last couple of seasons.

Ronaldo departed Old Trafford for Real in 2009 for £80 million having won three Premier League titles and a Champions League under Sir Alex Ferguson.

He has gone on to establish himself as unquestionably one of the top two players in the world, winning another Champions League title in 2014 and recently breaking Real's all-time goalscoring record, per Squawka:

"

RECORD: Cristiano Ronaldo has scored 324 goals for Real Madrid, overtaking Raul (323) as their all time top scorer. pic.twitter.com/d8y21mjCIw

— Squawka Football (@Squawka) October 17, 2015"

While his only La Liga title with Madrid came back in 2012, it may well be that he feels he has achieved everything he can at Real and thus he could well decide to leave in the summer, especially if he is unhappy with Benitez. 

Ronaldo will be 31 years old in February, but he does not look to be slowing down or dropping off in quality.

Jamie McDonald/Getty Images

His current contract at the Bernabeu runs until 2018, and he will demand an astronomical transfer fee should he be sold on next summer—Calderon suggested a figure of around €100 million (£73.6 million), per Le Parisien (via Marsden).

United have shown in the past couple of seasons that they are unafraid to splash the cash, and Ronaldo would likely be worth the money in marketing revenue alone.

Furthermore, he could provide Louis van Gaal's side with the injection of quality they need to move back up into the elite of European football.