Djokovic got himself out of trouble to level at 3-3 in the second set after drilling a forehand long to gift his opponent a couple of break points.
"He was backing up his serve with really good and aggressive first shots in the rally".
Tsitsipas has now beaten Djokovic twice in three matches. Zverev said Federer started to play better after his exchanges with the umpire.
"[Stefanos] had the high-quality tennis and he played very well after his serve", the Serb added on the ATP Tour website.
Zverev won the quarterfinal matchup, 6-3, 6-7 (7), 6-3, and this short outburst took place in the deciding set of the match. "I just gave him enough time to really dictate the play... and he deserved to win".
"I always dreamt of beating those players and I see each match when I go out on the court as an opportunity to bring the best out of me". If I do get up there, I'm not going to be focusing on ranking targets or things like that.
Zverev scored one his biggest best victorious shocking Federer 6-3, 6-7 (6), 6-3 and claim his very first Top 10 win of the season. "He's a very mental player, I would say".
"Obviously it was an important match".
Zverev, who has burst into life after a hard season, missed five match points in the second set, with Federer finding some magic to recover from 40-0 at 6-5 and then saving two more match points in the tie-break.
Prior to Friday's match, Fognini said Medvedev was one of the most risky players to face. Maybe I was favourite also going into this match, but Sascha came out and had no serving issues today.
"I told him at the net that he showed great character, that he was strong... So it's all good that the umpire got involved too".
Zverev ended 11th-seeded Italian Matteo Berrettini's run by taking their semifinal 6-3, 6-4, ending the match on an ace, one of 11 he had.
With these new faces, there will be a new Shanghai champion and for the first time in 20 years at a Masters event (1999 Hamburg), all four semifinalists are under 24.
It's been a disappointing week where not much has gone for us, and indeed not much has gone for the big names in the draw, with Novak Djokovic and Roger Federer dumped out on Friday by young players with ambitions to dethrone the elite duo eventually.
In fact, I think Medvedev is a decent price at [1.50].