
World Number 2 Roger Federer heaped praise on Serena Williams and described her as the greatest player to have played the Tennis sport.
"She [Serena] had a totally different upbringing - I came up through Switzerland with the federation, she did it with her dad and her sister. It's an amazing story unto itself - and then she became one of the greatest, if not the greatest tennis player of all time," Federer said.
Williams has won a record 23 Grand Slam titles in women's singles in Open Era.
The 36-year-old also moved ahead of Steffi Graf with her record seventh Australian title in 2017.
On being asked about his views on Serena-Venus Williams to compete as a wild-card entry at Roland Garros, Federer said, "I'm in full admiration of Serena. And Venus, too, by the way. It's incredible they're all still at it. Rafa's still playing, I'm still playing, Serena and Venus are still playing-and it seems like they love it more than ever."
"We know [Serena] is all the way up there. I'm probably up there with somebody, somehow. Maybe there's a group, a best of five - and if you're in that group, you should be pleased and happy. Tennis is a funky sport when it comes to that stuff," the world number 2 concluded.
Serena, who was blessed with a baby girl in September last year, returned to the court in March, but is yet to win a title this year.