Olympic absentee Stan Wawrinka will test his recent back injury as the Swiss opens his campaign at the ATP-WTA Cincinnati Masters in the second round against Jared Donaldson.
 The young American beat experienced Spaniard Nicolas Almagro 6-3, 7-6 (7/2) yesterday, advancing before afternoon rain returned on what promises to be a difficult scheduling week.
 The hardcourt test is the final major tune-up prior to the start of the US Open in a fortnight. Wawrinka is seeded second behind Rio gold medalist Andy Murray, who owns two Cincinnati titles.
 Double Grand Slam champion Wawrinka had been set to travel to Rio but called off what would have been the 31-year-old’s third Olympic adventure a few days before the start.
 The Swiss said that he did not want to risk what has been a solid season of three titles by playing when he was unfit at the Games.
 “It was tough to make the Olympic decision,” Wawrinka said after learning he would line up against the up-and-coming 123rd-ranked Donaldson, aged 19.
 “But it would have been a risk for me to have played. I went back to Switzerland (after Toronto ended two weeks ago) and saw the doctor. I was eight days out of tennis but I picked up a racquet a week ago and then travelled to Cincinnati. The back is not so bad, but I need to take some days out of tennis for rehab and work with the physio.”
 Wawrinka said he was a devoted viewer of the Olympic event which ended at the weekend with Murray beating Juan Martin del Potro in the gold medal match. Murray delayed his Rio departure until Monday to celebrate his second Olympic title and was due in Cincinnati later.
 “I watched it a lot — it was not easy not to be there. I have some great memories from Beijing (doubles gold medal with Roger Federer) and London. In Beijing I stayed in the athlete village,” Wawrinka said. “I wanted to do the same in Rio, But my body was not ready to be fully fit. Right now, I’m confident and ready to play. There is still a lot of tennis to play this season.”
 France’s Julien Benneteau earned the first upset win of the week as he put out Spanish 10th seed David Ferrer 6-4, 2-6, 6-4. Injury comeback hope Kevin Anderson of South Africa reached the second round when Alexandr Dolgopolov — a semi-finalist here last year from a qualifying start — was unable to carry on after losing the first set 7-5.
 Uruguay’s Pablo Cuevas beat Californian Sam Querrey 4-6, 7-6 (7/5), 6-3, finishing just before the rain arrived.
 Meanwhile, top seed Serena Williams gave up a wild card entry in Cincinnati after complaining of a shoulder injury. The world number one, who is being chased in the rankings by German Angelique Kerber, took a free entry only last week and was seeded atop the draw.
 But the 34-year-old American reversed course abruptly and withdrew from the tournament yesterday. “I’m very disappointed I’m not able to compete as I was really looking forward to defending my title,” Williams said. “My shoulder inflammation continues to be a challenge, but I am anxious to return to the court as soon as possible.”
 The absence of Williams now opens the door to Kerber to make a run at the WTA top ranking. Williams has been No. 1 for 183 straight weeks and 306 overall. But Kerber can become number one if she wins the Cincinnati title.
 Williams took a wild card spot to get into the draw. She will be replaced by lucky loser Misaki Doi of Japan. Doi moved into the second round and will face American Christina McHale, who beat Zheng Saisai of China 6-2, 6-2.
 Australian Daria Gavrilova defeated Caroline Garcia of France 7-5, 6-3; Latvian Jelena Ostapenko stopped Anna Karolina Schmiedlova of Slovakia 1-6, 7-6 (8/6), 7-6 (7/5).
 Ukrainian Lesia Tsurenko defeated China’s Zhang Shiau 6-3, 6-3 while American CoCo Vandeweghe put out Italian Sara Errani 4-6, 6-3, 6-4. Croatian Donna Vekic shocked newly married former world number one Ana Ivanovic 6-4, 6-2.
 In men’s play on a day interrupted by rain, France’s Julien Benneteau earned the first upset win of the week as he put out Spanish 10th seed David Ferrer 6-4, 2-6, 6-4.
 Injury comeback hope Kevin Anderson of South Africa reached the second round when Alexandr Dolgopolov — a semi-finalist here last year from a qualifying start — was unable to carry on after losing the first set 7-5.
 Marin Cilic reached the second round by beating Serb Viktor Troicki 6-3, 6-4, while Atlanta tournament champion Nick Kyrgios saw off Frenchman Lucas Pouille 6-2, 7-5. Bulgarian Grigor Dimitrov shrugged off a first-round Olympic loss to defeat Gilles Simon 6-1, 6-3 while US teenager Reilly Opelka put out Jeremy Chardy 3-6, 7-5, 7-6 (11/9).