Tomas Berdych defeated Juan-Martin del Potro 6-1 6-4 in the final of the Japan Open on Sunday.
However, Berdych admitted his victory over del Potro was made easier by a stomach ailment which inhibited the Argentinean.
The Czech right-hander claimed his fourth career title against an opponent who showed signs of discomfort throughout the match.
Del Potro was forced to leave the court at one stage and Berdych conceded, while serving well throughout, that his task had been made easier by the Argentinean's illness.
"Everyone could see he had some problem," said Berdych. "But he took some pills and was getting back into the match."
"It might have been different if Juan-Martin was feeling better but I served well and everything came together."
Berdych got off to a rousing start to claim the first set in quick time.
The second set was more challenging, but Berdych held off del Potro's three attempts to break in the match and finished off his foe in one hour and 18 minutes.
Del Potro had no answer for Berdych's first serve. The Czech won 27 of 31 points on his initial serve, enabling him to control the flow of the match. Berdych also took advantage of Del Potro's second serve, winning 56 percent of those points.
The 12th-ranked Del Potro, 20, had never won on the ATP Tour before capturing four consecutive tournaments during the summer, and he followed that with an impressive quarter-final effort at the US Open.
"I took some medicine and I started playing a little bit better but it was too late," del Potro said. "I didn't have any chance today. He played great. It was his day."
In the women's tournament Caroline Wozniacki won her third title of the season with a 6-2 3-6 6-1 victory over fifth-seeded Kaia Kanepi of Estonia.
Wozniacki, the world number 16, has won all three of her trips to finals this year, having claimed titles at Stockholm and New Haven prior to this.
After failing to make it past the first round in her past two tournaments, the 18-year-old Dane turned things around here, losing only two sets in four matches.
"I'm really excited to win this tournament," Wozniacki said.
"I had some tough draws against some great players the last few weeks, but both matches were close and I still felt I was playing well."
Kanepi advanced to her second career final after dispatching Canadian Aleksandra Wozniak 6-4 6-4 in the semi-finals.
Kanepi, who is ranked 33rd in the world, was a finalist at Hasselt in 2006 and has semi-final appearances at Acapulco and Seoul this season.
"It was a good match. I definitely had my chances in the second set and I hit a lot of good winners, but she's very aggressive and if you don't keep up with her, she will win," Kanepi said.
ATP Singles, Final of the Japan Open, Tokyo
9-Tomas Berdych (Czech Republic) def. 5-Juan Martin Del Potro (Argentina) 6-1 6-4
WTA Singles, Final of the Japan Open, Tokyo
1-Caroline Wozniacki (Denmark) def. 5-Kaia Kanepi (Estonia) 6-2 3-6 6-1