Novak Djokovic took the first step in his Cincinnati Masters title defence, winning a quick-fire second-round match 7-5, 6-1 over Sam Querrey.
But the tournament took another blow as more players withdrew with injuries, fearful of missing out in New York.
The back spasms which prevented Serena Williams form finishing the weekend Toronto final forced her withdrawal yesterday.
Djokovic though, got off to a poor start, dropping his opening serve thanks to three double-faults; but he quickly gained traction to crush his Californian opponent for the ninth time in 11 meetings.
He broke back in the sixth game for 3-all before breaking Querrey to win the first set and totally controlling the second for a 77-minute success.
“I had the nervous start, because, I had not played a match for four weeks,” he said after last competing against Roger Federer in the Wimbledon final.
“It took me a little time to really adjust, to also hit big serve that was coming sometimes more than 135 miles an hour.
“I didn’t have the greatest of starts. This was a tricky match, quality opponent, big challenge.
“But I’m happy to be tested right away, hopefully the next performance will be even better.”
Stan Wawrinka needed to struggle to beat former No. 3 and 2017 Cincy winner Grigor Dimitrov 5-7, 6-4, 7-6(4), repeating a win over the faltering Bulgarian from last week in Montreal.
Wawrinka had trouble holding a 5-1 lead in the final but was unable to profit from a pair of match points as he served for the win.
It took a tiebreaker and another defensive effort form the 34-year-old Swiss to finally go through to the second round after two and a half hours which completed with a 10th ace.
Meanwhile, Williams will find herself short of recent match practice when the US Open starts a week on Monday.
She pulled the plug on her first-round start in the Midwest after a training session in the morning.
“I came her on Sunday and have tried everything to be ready to play tonight,” she said in a statement.
“I was still hopeful after my practice this morning. But unfortunately my back is still not right and I know I should not take to the court.
“I promise I’ll do my best to be back here next year.”
Word from the camp of the 10th seed was released shortly before her intended match with Zarina Diyas; Williams was replaced in the draw by American Jessica Pegula, surprise winner of the Washington title in recent weeks.