Manchester United, Manchester City and Chelsea are monitoring Cristiano Ronaldo's contract row at Real Madrid. The Mail on Sunday says Ronaldo's ambition to become the world's best paid footballer is causing a growing rift with Real Madrid that has alerted Europe's big-spending clubs.

Along with the Premier League trio, PSG are also eyeing the ex-United star.

Ronaldo's salary at Real sees him 10th in the high earners' list at £7.98million net, around half what Samuel Eto'o earns at rich Russian club Anzhi.

His immediate target is a 50 per cent increase to around £11.8million net.

But the issue is complicated by Ronaldo's dissatisfaction at his image rights - 50 per cent of which are owned by the club - and Spain's revised tax laws.

Ronaldo earns £13.45million from off-pitch deals.

That means he is effectively paying his own wages at the Bernabeu.