Some observers were predicting that 2019 would be the year that Federer and Nadal would finally give way to a younger generation of stars, with Alexander Zherev, Karen Khachanov and Stefanos Tsitsipas considered the most likely young players to break through.
Federer refused to blame the early umpire controversies for his defeat, saying instead his inability to get a look in on Tsitsipas' serve was the reason he fell short. As well, this is the first time Tsitsipas has even won a main-draw match in Australia.
While Federer must head home licking his wounds, Rafael Nadal's prospects of winning a second Australian Open title 10 years after his first are looking every more rosy. He did beat him in US Open a few years ago.
John McEnroe declared the result to be a changing of the guard, but Federer is not ready to hand over the mantle yet, and announced he had chose to play on clay this year.
Six-time Australian Open victor Federer will need to overcome a challenge from world No. 50 Taylor Fritz if he is to advance to the fourth round of the Australian Open. A win there would set up a semi-final clash against the victor of Rafael Nadal and Frances Tiafoe, another youngster in an exciting vein of form.
Rather like when he wilted in the heat against John Millman at the same stage of the US Open, this was a reminder that Federer is trying to achieve unprecedented things, and even the greatest can not win the ageing game. "Cost me the game tonight". It was actually not Rafa, Djokovic, but some other players that have beaten him in the past US Open. "Now I'm trying to do it for me". Congrats @StefTsitsipas, attacking tennis with such mature composure on the big stage @AustralianOpen.???? Not expert level. Just by watching matches, highlights. Meanwhile, Federer was upset with a replayed point which prompted him to say to James Keothavong, "I think you have a bad conscience about giving him two warnings". The video said "silencer".
"He commented "silencer" (the name of the celebration) and he put a crown, two muscle emojis", said Tiafoe.
I know he's unsafe. "I was just serving well".
"My idol today became pretty much my rival", Tsitsipas said. One he beat at his own game, in some respects.
Stefanos Tsitsipas: I haven't watched that match here in Melbourne yet.
So, a changing of the guard, as McEnroe declared it? "I can say I have missed it, I did the right thing skipping it last year, the year before as well, and the year before that I was injured". From that standpoint, nothing new there.
A tie-breaker was eventually needed to decide the outcome, with Kvitova - back in action for the first time since losing to Naomi Osaka in the Australian Open final - reeling off five successive points to seize control.