Nadal to skip ATP Asian swing due to knee injury

World number one Rafael Nadal said yesterday he would skip the Asian leg of the ATP tour to recover from the knee injury he picked up at the US Open, a decision that will boost Novak Djokovic’s chances of ending the year top of the rankings.Nadal was forced to retire during his semi-final against Argentine Juan Martin del Potro at Flushing Meadows with what he later said was tendinitis in his right knee, and will now also miss next month’s tournaments in Beijing and Shanghai.Djokovic, seeded sixth at the US Open, beat Del Potro in the final to claim his second Grand Slam title this year and rise to third in the rankings, behind Nadal and Roger Federer.“I had to retire from the semi-finals of the US Open and this past Monday I was with doctors in Barcelona to review the situation with my knee,” Nadal wrote on Twitter.“While my knee problems are nothing new, I have decided together with my medical and technical team not to participate in the Asian tour to recover.”The Spaniard tops the world rankings with 8,760 points, 1,860 ahead of Federer and 2,315 more than in-form Djokovic.With Federer cutting the number of tournaments he plays — the Swiss only took part in events in Shanghai, Basel and the ATP finals after last year’s US Open — Djokovic is now favourite to unseat Nadal as world number one. nThree-time Grand Slam champion Stan Wawrinka advanced to the quarter-finals of the St Petersburg Open with a win over Russian fourth seed Karen Khachanov in two tie-break sets.The 33-year-old Swiss star Wawrinka, a wildcard entry, knocked off world number 24 Khachanov 7-6 (12/10), 7-6 (7/1) and awaits the winner between defending champion Damir Dzumhur and Guido Pella.“I’m really happy as the level of my play was really good today,” Wawrinka said. “We both played really well, really aggressive. I was expecting a tough match and it was really tough. My level was great and I’m really happy with everything that took place on the court today.”Wawrinka, the former world number three, who is now down at 88 after a battle with injury, started confidently breaking his rival’s serve early.But the Swiss, who has been struggling to find his best form since returning to the ATP Tour after two operations on his left knee a year ago, suddenly lost his nerve to allow the local favourite to break twice in succession.Khachanov, 22, was serving for the set but Wawrinka broke again to level and force a tie-break, closing it out at the sixth attempt having also saved two set points.Wawrinka then raced through another tie-break to seal victory over Khachanov in the first meeting between the pair.Fifth-seeded Spaniard Roberto Bautista Agut and Canada’s Denis Shapovalov, the seventh seed, reached round two with respective wins over qualifiers Luca Vanni, 7-5, 6-2, and Adrian Menendez-Maceiras, 7-6 (7/3), 6-2.nJapan’s Kei Nishikori returned to action for the first time since losing in the US Open semi-finals with a 7-6 (7/4), 6-3 win over defending champion Peter Gojowczyk in the Metz second yesterday.World number 12 Nishikori defeated the 45th-ranked Gojowczyk in 94 minutes and will face either Ugo Humbert of France or Georgia’s Nikoloz Basilashvili for a semi-final place. Nishikori made the semi-finals at the US Open earlier this month but was easily defeated in straight sets by eventual champion Novak Djokovic.nJapan’s Naomi Osaka cruised to victory in her first match since lifting the US Open title, beating Dominika Cibulkova 6-2 6-1 in the last-16 at the Pan Pacific Open in Tokyo yesterday.Osaka, who stunned Serena Williams to become Japan’s first grand slam singles champion earlier this month, produced another display of fearless power-hitting to put away Slovak Cibulkova in just under an hour.