Serena Williams’ fierce competitive streak is what sets up apart and puts her on track to become the greatest female tennis player of all time, according to Roger Federer.

Speaking to Sport360 earlier in the week, the 18-time Grand Slam champion spoke of his admiration for his fellow Australian Open champion’s longevity.

“I admire everything she’s doing and has done,” he said. “I thought she was ready to check out there for a while. But she’s hung on and she’s found new ways of doing things. She’s gotten healthy again as well, she was very unfortunate on a few occasions.”

Serena’s success at the Rod Laver Arena was her 23rd Grand Slam success, which took her past the Open Era record of 22 she had previously held with Stefanie Graf and to within one of Margaret Court’s all-time record. Federer’s victory in the men’s tournament meant that both trophies were won by 35-year-olds.

“People who have done it for a long time and who are older now but are still super eager and super willing and Serena is exactly like that,” said the Swiss. “She’s a fierce competitor and on the way to becoming the greatest of all time. It’s wonderful to see her do it for sure.”

Federer’s comments come little more than two weeks after Andy Roddick called Serena one of the greatest athletes of all time. The American, who grew up training alongside Williams in Florida, described her as “not just one of the greatest women athletes of all time but one of the greatest athletes of all time.”

He added: “We need to enter her into the conversation with [Michael] Jordan and [Muhammad] Ali. I think that’s where the respect lies and where the conversation needs to go after the acknowledgement of what she’s done for women in sports.”