Roger Federer stared hard at the future and in the unyielding figure of 20-year-old Stefanos Tsistipas found that it was too much for him.
The defending champion was knocked out of the Australian Open courtesy of a nerveless display from the young Greek, who seized his chances to win 6-7, 7-6, 7-6, 7-6 in three hours and 45 minutes.
Federer, of whom it is so easy to forget is 37, spurned copious opportunities against the world No 15, whose previous best at a Grand Slam was his little noticed fourth round at Wimbledon last summer.
Stefanos Tsitsipas made history as he produced a stunning 6-7, 7-6, 7-5, 7-6 win over Roger Federer at the Australian Open
The defending champion was stunned by the 20-year-old Greek opponent as his title defence was ended in round four
It proved an extraordinary match in what many feel is a strong sign that there is a changing of the guard at the top of the game
Tsitsipas was overwhelmed after winning the final tie-break as he struggled to hold back tears standing on the court
He now plays Spain's Roberto Bautista Agut, who has powered on from his defeat of Andy Murray on the opening day.
'There is nothing I can describe it, I'm the happiest man on earth right now,' said Tsitsipas. 'I actually from the very beginning I kept the mindset to believe in myself and my capabilities. Roger is a legend, he showed such good tennis over the years, I have been analysing him since the age of six. It was a dream come true facing him.
'It's very important to have an aggressive mindset and not think too much of what is going to happen. I didn't lose my patience, that was key to save the break points. I haven't seen such a loud crowd in my life.'
