Daniil Medvedev and Stefanos Tsitsipas have played each other 4 times in the past.
Djokovic, the defending champion, lost to sixth-seeded Stefanos Tsitsipas 3-6, 7-5, 6-3.
The Greek's victory also means that Djokovic will surrender his number one spot in the ATP ranking to Nadal. Federer, who was given a warning for "unsportsmanlike conduct" at the end of the second set, vented at the umpire after not being told new balls were in play.
"I knew if I keep playing the way I was playing in the first two sets I was going to have a chance in the third as well".
"He has a very different tennis from most of the players that I have been playing against this year", said Tsitsipas. "He was backing up his serve with really good, aggressive first shots in the rally", Japan Open victor Djokovic told reporters. "I started well in the first set, but I wasn't sharp enough". "I just gave him enough time to really dictate the play... and he deserved to win".
The world No. 3 was beaten 6-3, 6-7 (7-9), 6-3 in the quarter-finals by 22-year-old Alexander Zverev in a 2hr 4min encounter that saw him lose his cool after receiving a point penalty - his first in a "long, long time".
One of 26 unforced errors from Djokovic gave Tsitsipas, who produced an array of searing backhand and forehand winners, three break points and he grasped the opportunity to take a 3-1 lead in the third before going on to seal his place in the penultimate round. The only time he lost a hard-court match after winning the first set was against Gael Monfils in Rotterdam.
One victory away from reaching a sixth straight final. "The head-to-head is obviously a great thing to have, but more importantly for me is it was a match to maybe turn my year around a little bit, and the Race to London is also very important", Zverev said.
"If some top players like Fabio can say this about me, it shows that I'm on the good way, I'm playing good, and it's not easy to play against me", Medvedev said.
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