CINCINNATI - Stan Wawrinka polished off a two-day victory to reach the third round of the rain-plagued ATP-WTA Cincinnati Masters on Wednesday as the Swiss takes aim at a return to the year-end season finals in London.
Stan Wawrinka of Switzerland serves to Jared Donaldson of the United States on August 17, 2016 in Mason, Ohio
The second seed at the last major tune-up prior to the US Open defeated 122nd-ranked American teenager Jared Donaldson 2-6, 6-3, 6-4.
The match began Tuesday night but was held up several times due to rain before being cancelled late in the evening.
The victory gives the two-time Grand Slam champion fresh motivation heading into the final third of the ATP campaign.
"I really want to qualify for London (eight-man World Tour Finals)," Wawrinka said. "That's my main goal for the rest of the season.
"I have to stay inside the top eight," added the world number four, who is bidding for a fourth straight London appearance.
Wawrinka said that advancing in steamy Cincinnati was a challenge against rising opponent Donaldson.
"It was two different matches between last night and today. It was a very difficult first match, he played well, and very aggressive.
"It was difficult to play in the heat today, I'm happy to take a win after not playing for two weeks," the Swiss said, after a back injury ruled him out of the Olympics.
"I'm very happy to win this match. I had to get my bearings on court again."
Japan's fifth seed Kei Nishikori joined Wawrinka in the third round with a 6-3, 6-2 defeat of experienced Mikhail Youzhny. Frenchman Jo-Wilfried Tsonga, seeded seventh, beat American Reilly Opelka 7-6 (7/5), 7-6 (7/3).
Eighth seed Dominic Thiem won his first match since late June at Wimbledon, defeating Australian John Millman 7-5, 6-1.
As first-round play got caught up after days of wet weather, Juan Monaco knocked out Los Cabos title-winner Ivo Karlovic 6-4, 6-4; France's Nicolas Mahut beat 15th seed Roberto Bautista Agut 7-6 (7/2), 2-6, 6-3.
In the women's draw, third seed and 2015 finalist Simona Halep started with a 6-3, 6-1 defeat of Annika Beck.
"I played pretty well today. I felt the game and the balls were a little bit heavier because of the rain and the humidity. But it was good for me," Halep said.
"I was a little bit nervous before the match because I had two weeks without matches. The first match of the tournament is tough. Now I'm more relaxed and I'm looking already forward to the next one."
US Open finalist Roberta Vinci stopped Tsvetana Pironkova 7-5, 6-3. Hungarian Timea Babos upset Swiss 13th seed Belinda Bencic 7-5, 6-2.