Novak Djokovic says he does not “know on what basis” three-time Wimbledon champion John McEnroe likened him to golf star Tiger Woods.
Djokovic, 30, has lost all four Grand Slam titles which he held last year and slipped to fourth in the world.
Woods, a 14-time golf major winner, has struggled for form after marital problems and injury in recent years.
McEnroe said Djokovic “had some off-court issues with the family”, but the Serb said he took the claims “lightly”.
“He’s well known for his bold comments and not caring too much about being politically correct and saying whatever is on his mind,” Djokovic said about American McEnroe.
“I don’t take anything personally.”
Djokovic, a 12-time Grand Slam champion, said last month that 2017 had been his toughest year in tennis.
As well as losing all of his major crowns, he slipped out of the world’s top two for the first time since 2011 and split with his coaching team.
However, the former world number one has rediscovered his form during the grass-court season.
Djokovic won the Eastbourne title – his first pre-Wimbledon tournament for seven years – and has since cruised into the third round at SW19.
He was leading 6-3 2-0 in his opening match when opponent Martin Klizan retired hurt, then eased past Czech Adam Pavlasek in straight sets on Thursday.
But McEnroe, 58, claimed Djokovic’s form over the past 12 months suggests the Serb is being distracted by off-court issues.
Djokovic is married to childhood sweetheart Jelena, 31, who is pregnant with their second child.
“If you’re distracted you’re not the same player,” said McEnroe on the BBC’s Today at Wimbledon programme.
“The person that comes to mind immediately with Novak is not a tennis player, it’s actually a golfer: Tiger Woods.
“Woods had the issues with his wife and then he seemed to go completely off the rails and has never been even close to being the same player.
“So we’re starting to say: ‘Wait a minute, is this possible with him Djokovic?'”