(Reuters) - World number one Novak Djokovic cruised through his opening match at the Western & Southern Open in Cincinnati on Wednesday, while Stan Wawrinka had to dig deep to beat Borna Coric and conceded his thoughts had been far from tennis over the past few days.
Andy Murray, who beat Djokovic in the Rogers Cup final on Sunday and moved up to second in the world rankings, had a tough second round outing against Mardy Fish but came through 6-4 7-6(1), while Rafa Nadal also advanced after beating Jeremy Chardy.
French Open champion Wawrinka said he had yet to receive an apology from Nick Kyrgios for the Australian's incendiary comment during their match last week.
Kyrgios, 20, drew the ire of the tennis world in Montreal after he insulted Wawrinka at the Rogers Cup, saying that another Australian player, Thanasi Kokkinakis, had slept with Wawrinka's girlfriend.
Though Kyrgios later apologized via Twitter for his comments, he was slapped with two separate fines by the ATP who also raised the possibility the Australian could be suspended.
Wawrinka did not hear the comment at the time, only learning later that it had been audible on television. He admitted after his victory on Wednesday that the past week had been difficult.
"For the past few days for sure my head was not really into the tennis," Wawrinka told Sky Sports television after his 3-6 7-6(3) 6-3 win over Croatian teen Coric.
"What happened people don't see exactly what the consequences are for everybody so I'm trying to put away.
"Today I'm happy with the way I fight. I was playing really bad tennis but most important is the win."
Wawrinka was then asked if he was happy with the way that Kyrgios, who lost his opening match in Cincinnati, had apologized for the incident.
"He didn't apologize so no, but I prefer not to talk about him, thank you," said Wawrinka.
Top seed Djokovic cruised through his opener against Benoit Paire, beating the Frenchman 7-5 6-2 to set up a third-round clash with Belgian 13th seed David Goffin.
Murray, who ended an eight-match, 25-month drought against the Serb on Sunday in Montreal, was given a thorough test by the 33-year-old Fish, who has said he will retire after the Aug. 31-Sept. 13 U.S. Open.
After taking the first set 6-4, Murray let frustration creep into his game and he smashed his racquet after being broken in the 11th game of the second set, which gave the American the chance to serve out to even the match.
Murray broke right back, however, then dominated the tiebreak to close the match out after midnight.
"I forgot how tricky Mardy was to play against," Murray said after improving his career record to 5-4 against Fish.
"He takes the ball incredibly early and the ball comes off his racquet so quick sometimes. I found it very tough ... I didn't feel that confident striking the ball, which is quite different to last week,"
Eighth seed Nadal, swept aside by Kei Nishikori in the Rogers Cup quarters, beat Frenchman Chardy 6-3 6-4. The Spaniard showed some positive signs of returning to form but still had to stave off nine break points.
"I am working very hard to find my best game again," said Nadal, who has been hampered by a string of injuries over the past couple of years.
Reporting by Andrew Both in Cary, North Carolina, and Tim Wharnsby in Toronto. Editing by Frank Pingue and Peter Rutherford