Roger Federer says he was surprised to see Novak Djokovic get beaten by Stefanos Tsitsipas as the top two seeds both exited the Shanghai Masters.
World no 1 Djokovic won the first set 6-3 and appeared on course to complete a routine win and reach the semi-finals.
But Tsitsipas showed admirable resilience to fight back and win the second set 7-5.
And in the final set, the Greek was too good for Djokovic as he sealed a 3-6 7-5 6-3 win and became just the second player this season to beat the ‘Big Three’ of Djokovic, Federer and Rafael Nadal.
Later in the evening, Federer suffered an upset of his own as Alexander Zverev beat him in three sets.
It means the tournament is the first since 1999 with four semi-finalists under the age of 24.
After his match, Federer was asked about the fact the tournament will have a new winner this year.
And the Swiss hailed the young generation of players as he expressed surprise at Djokovic’s defeat.
He said: “Yeah, I mean, they’re knocking on the door big time, the young guys. It’s exciting. They’re great.
“It’s really open now, I think, for the finish of this tournament.
“I think it’s also quite exciting that, how do you say, the speed of the court is fast. So you see some different rallies played.
“Guys have to maybe come into the net a little bit more, as well. You can throw in the serve-and-volley if you want to.
“But, yeah, it was definitely surprising to see Novak lose a little bit, even though Tsitsipas has played great so far.
“Maybe I was still the favourite going into this match, also, but Sascha came out and had no serving issues today and really was able to produce a great game like he did against me already in London.
“Yeah, it’s an exciting time in tennis. Nothing new there. So it’s good.”