Magnus Norman, Stan Wawrinka's coach, says that the Swiss is "very doubtful" for Cincinnati, though the world No. 4 appears to be training again.
Wawrinka withdrew from the Olympics, citing a back injury that he said prevented him from playing. He published photos of himself on the practice court on social media this week, but has not publicly set a return date.
Getting back on the practice court !! !! pic.twitter.com/VrqDvIQfxn— Stanislas Wawrinka (@stanwawrinka) August 9, 2016
Asked if he would be accompanying Wawrinka in Cincinnati, Norman indicated that Wawrinka's participation was questionable, but noted that a decision would be made in the "next few days."
Norman was not with Wawrinka last week in Toronto, where the two-time Grand Slam champion reached the semifinals. Despite the impressive showing, Wawrinka looked unusually uncompetitive in the second set of his 7-6 (6), 6-1 loss to Kei Nishikori.
Wawrinka's withdrawal would further deplete the Cincinnati field. Roger Federer will not play again this season because of a knee injury, though he plans to return to the tour next season.
It’s also unlikely that Novak Djokovic will play Cincinnati. The Western & Southern Open is the only Masters 1000 event that the Serb has not won in his career.