World number one Novak Djokovic was stunned in the Shanghai Masters quarter-finals by young Greek Stefanos Tsitsipas in three sets on Friday.
He will now play another highly promising talent in his Saturday semi-final match against 23-year-old Daniil Medvedev.
The seventh-ranked Tsitsipas recovered from losing the opening three games in just seven minutes to shock the reigning champion 3-6, 7-5, 6-3.
He sealed the deal with a gleeful smash and held both arms aloft.
Tsitsipas has now defeated the top-ranked Serbian twice in their three matches -- further proof that the 21-year-old is a serious contender at the top of men's tennis.
After a dreadful start, he found his feet in the second set, winning on a tie break, then went 3-1 up in the decider when Djokovic planted his forehand wide on the third break point.
It was a double celebration for the young Greek, who has also confirmed his place in the prestigious season-ending ATP Finals.
He did so after fourth-ranked Medvedev tamed self-styled "wild horse" Fabio Fognini 6-3, 7-6 (7/4) to canter into the semi-finals. Fognini was vying for a place at the Finals.
Djokovic, 32, said that he is fully recovered from a shoulder injury.
He did not drop a set in winning the title in Tokyo and had carried that form into Shanghai -- until he came across Tsitsipas.
Medvedev -- another of the next generation -- sent down 12 aces to help see off Fognini and said: "I don't know what happened, my serve was crushing it."
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