Cristiano Ronaldo has reportedly joined the growing number of celebrities who collect luxury watches.

The Real Madrid and Portugal footballer - currently the most expensive player in football history - reportedly owns several valuable watches, including a £70,000 Franck Muller timepiece, according to The Sun.

His other investment choices include Rolex, Cartier and Breitling - and also Hublot, sponsors of his former team Manchester United.

An Old Trafford source told the British tabloid: "Ronnie is becoming more mature with his money and, although he loves cars, he now wants items which hold value.

"He has been told how some watches increase in value over time and he has developed a great eye for these things."

Apparently, watch investing is becoming a growing source of enjoyment and competition between Ronaldo and his teammates.

"A few of the United lads compete over cars and watches, but Ronnie always seems to be one step ahead."

Other celebrities to recognise watches as a wise investment including Michael Schumacher, Arnold Schwarzenegger, Bruce Willis and Sylvester Stallone.