Zverev had 4-1 30-0 in the third set. Lost the set.
Then 3-0 40-15 in the fourth set. Lost the match.
3/12 on break points. Zverev left that one behind him.
Clutch again from Djokovic, but 55 unforced errors from Novak shows he is not playing at his best either. Don't know much about Karatsev, but sounds like he's an aggressive player who will go for everything and has nothing to lose.