Manchester United are on red alert as Cristiano Ronaldo's contract impasse with Real Madrid continues with no end in sight. Ronaldo has been left fuming that the Spanish giants are refusing to negotiate a new deal and fears Real are using him as nothing more than a cash cow, says the Daily Star.

And that has left the 28-year-old ready to quit the Bernabeu in the summer, with United the clear favourites to land his signature in a £55m deal.

The Portugal star's current contract has a clause written into it which sees Real rake in 40 per cent of the player's individual personal endorsements.

Given that Ronaldo is one of the biggest stars in the sporting world, that effectively means he pays the club more out of his own pocket than Real actually pay him in wages.

Though money is not the major driving force in his career, the player feels Real should be far more flexible in their stance and should reduce the cut they take.

 Are the stars aligning? Could Ronaldo return to United? Give us your shout below...