Tomas Berdych recorded the fourth tournament victory of his career when he beat an ailing Juan Martin Del Potro 6-1 6-4 to win the Japan Open in Tokyo.

The Czech No.9 seed who has not won a tournament since Halle last year, held serve throughout the 77 minute encounter, converted 3 of 8 break point chances and blasted 11 aces past the Argentine who was suffering from an upset stomach.

Del Potro despite the loss will enter the top 10 for the first time at 9 in both the race and the rankings and is within touching distance of qualifying for the Shanghai Masters Cup having won four maiden events this year.

"I'm feeling very good because everything is good for me now," said Del Potro, despite his defeat. "The results are coming and everything is coming together. I have the chance to qualify for the Tennis Masters Cup, I need one or two more results and I'm working to earn this. I hope to continue this good form and qualify for Shanghai."

A delighted Berdych who has an outside chance of qualifying for Shanghai said: "Today I think he had a little bit of bad luck and I think he didn't feel well on the court from the beginning. But I think in the second set he was getting pretty close and I'm very happy that I finished it the way I did."