MONTREAL, Aug 4: Roger Federer and Rafael Nadal begin the countdown to this month's US Open as the top two in the world resume their rivalry atop the field at the Montreal Masters.

The event, which begins on Sunday in an effort to attract more fans, is the first of back-to-back elite events as the big names swing into action on the hard courts of North America.

Federer has not played since lifting a fifth straight Wimbledon title, beating Nadal in five sets on the grass.

The 20-year-old Spanish number two took a week off, then won another clay trophy along with a flash Mercedes car at the Stuttgart ATP stop.

While top 10 Americans including Andy Roddick and James Blake have played a limited schedule at home in recent weeks, Europeans have been holding off their debuts on the cement.—AFP