Roger Federer has taken a rare foray into the GOAT (greatest of all time) debate, calling Serena Williams "one of the greatest, if not the greatest tennis player of all time" across the sport.
Federer is on the cover of the current WSJ. Magazine, accompanied by a feature story which notes while Rafael Nadal has been considered Federer's greatest rival, Federer and Williams are more similar in age and tennis achievements.
Williams, 36, has 23 Grand Slam singles titles, one behind Margaret Court's record of 24 titles. Federer, 36, has 20 Grand Slam titles, the record on the men's side. Williams recently returned to tour following the birth of her first child, and next week in Paris will play her first Grand Slam tournament since her victory alongside Federer at the 2017 Australian Open.