It seems odd to say this now, but when Roger Federer breached the 20 Grand Slam mark at the 2018 Australian Open, it appeared unbeatable. It so happened though, the GOAT (if you dispute this, then do not read any further) just walked through a door, and because he was so well-mannered, held it open for others to pass through.
That Australian Open was one with many strange happenings, which, at the time, seemed to portend a different future for men’s tennis. Federer beat Marin Cilic to win the title, and seemed to have got his mojo back. Rafael Nadal