The top stars of men's tennis are divided on how long they should be playing.

Novak Djokovic, responding Wednesday to Roger Federer's pitch for more five-set matches during the season, said he wants to go the other way, even reducing Grand Slams to three sets to keep the attention of younger fans.

"I would have even Grand Slams best of three, to be honest," Djokovic said in an interview on the Tennis Channel. "This new generation of tennis fans and millenials, they don't have the great attention span. They want things to happen very quickly. So for the players as well and to attract more people, more viewers of a younger audience, I think we have to keep tennis matches dynamic, shorter and no shot clock."

A day earlier, Federer had proposed adding five-set match to Masters 1000 events and the ATP World Finals.

"On the ATP Tour, we actually don't have any best-of-five-set matches. They're all at the Slams, Davis Cup and at the Olympics finals," Federer said in his Tennis Channel interview. "I feel like that's a bit of an opportunity wasted. I know it's also for player protection, for injuries. ... I think that's a bit of a pity, but I understand the reasons."

Attrition has been an issue for the "Big Four" of the men's game. Federer, Djokovic, Rafael Nadal and Andy Murray have all dealt with injuries that have forced them out of at least one Grand Slam since 2016, and Federer recently withdrew from last month's Rogers Cup, citing his schedule as the reason.

Murray, who hasn't played a Grand Slam since last year's Wimbledon due to a hip injury, was split in his opinion, telling The New York Times that he enjoyed playing five-set matches but found them less enjoyable as a spectator.

"As a player, I really like best-of-five. It's been good to me," Murray said. "I feel like it rewards the training and everything you put into that. But then, when I sat and watched the match -- that Nadal-[Juan Martin] del Potro [Wimbledon quarterfinal] in the commentary booth -- it was an amazing match, it was a brilliant match, but it was really, really long to sit there as a spectator for the first time."

Murray added that he thought this year's Wimbledon semifinals, in which both matches lasted more than five hours, was not "good for tennis."

"People that are sitting there during the week watching that all, I don't think you can plan to do that," he said. "A lot of people are going to be getting up and leaving the matches and not actually watching the whole thing."