Del Potro issues Grand Slam warning at Rogers Cup

Juan Martin Del Potro stormed to a 6-4 6-0 first round win over Finland's Jarkko Nieminen at the Rogers Cup Monday, the Argentine continuing his impressive comeback with the U.S. Open on the horizon.

Del Potro, the 2009 U.S. Open champion, is on the comeback trail after missing eight months of last season recovering from wrist surgery.

The 22-year-old opened the season with second round losses in Sydney but has been in red hot form since, posting a 34-7 record that included wins at Delray Beach and Estoril.

"I'm doing well this season, I have beaten top 10 players, there have been many good things for me in this year," said Del Potro, who was ranked 484th in February but has clawed his way back into the top 20.

"Of course, I'm looking forward for the next Grand Slam, it's my favorite and it will be my first time there since 2009, so will be fantastic for my confidence.

"But it's very tough every tournament for me after 2010. I was completely out of the circuit and now I'm trying to recover my game, my fitness, everything," he added.

Jo-Wilfried Tsonga, seeded 13th, was the top ranked player in action. The muscular Frenchman survived a couple of wobbles before knocking out Italian Fabio Fognini 6-4 7-6 (7-0). Swiss 14th seed Stanislas Wawrinka eased pass Argentine David Nalbandian 6-1 6-4 while Latvia's Ernests Gulbis, riding the momentum from his hard court win in Los Angeles, rallied past former world number one Juan Carlos Ferrero of Spain 3-6 6-1 7-5.

Novak Djokovic, Rafa Nadal, Roger Federer and Andy Murray, looking to win the title for a third successive time, return to action Tuesday for the first time since Wimbledon.

In evening ceremonies Djokovic accepted the ATP number one ranking trophy while Federer quietly celebrated his 30th birthday.