Novak Djokovic and Serena Williams have been trading parenting tips ever since their children were born a day apart - and now both are competing at the French Open.
Djokovic took care of business in his second round matchup, beating Jaume Munar 7-6 (1), 6-4, 6-4.
However, the former worldNo. 1 was left speechless after a baffling question from a reporter who asked if it was easier to be a father playing tennis than it was to be a mother.
After a pregnant pause, father-of-two Djokovic answered: "Well, I think it's obvious.
"I mean, what a woman has to go through, with the pregnancy and birth and then everything after that? I'm sorry to all the guys, but it's much more difficult for a woman," Djokovic told reporters at the French Open on Thursday.
"So that's why it makes it even more impressive when they make a comeback, and especially Serena after all she has done."
Williams, who won the 2017 Australian Open while pregnant, is making her Grand Slam comeback at Roland Garros this week. She gave birth to daughter Alexis Olympia Ohanian in September last year.
"It's not like she never won a slam and then now she wants to come back because she has something to achieve from that perspective," Djokovic added.
"After all she has achieved in sport to see her back and putting hours on the court and work and again and again, it's impressive. It's inspiring. It really is.
"She's the greatest female athlete of all time, probably, and she keeps on coming back and inspiring everyone. She uses tennis as a platform to do good things and that's why she's back. You can see how much she loves it.
"I love Serena. All the superlatives and beautiful words that you can think of she deserves it."