Nick Kyrgios has encouraged Rafael Nadal and Novak Djokovic to play at the Australian Open it would be a "disaster" if the 'Big Three' were missing.
Djokovic is on the entry list for the first Grand Slam of the year, which begins in three weeks, but has refused to verify if he has been vaccinated, throwing doubt on whether he will turn up.
The dominant 'Big Three' have won 20 Grand Slam titles each, and Kyrgios said tennis still needs them, starting in Melbourne next month.
"I honestly don't know Novak's current situation with anything Covid-related or what he needs to play," the colourful Kyrgios told the Melbourne Age newspaper.
"I hope he's had a good Christmas, and I hope he's able to play in the sport for as long as possible because I've voiced before I think Federer, Nadal and Djokovic need to be (playing).
"If all three aren't there, it's a disaster. It's an absolute disaster for the fans and the people that enjoy tennis.
"Yes, it's obviously a good opportunity for some of the younger guys to come through and make an impact, but as a whole, we do need them to be part of the sport."
The Australian Open starts at Melbourne Park on January 17.