After watching the last set of the Zverev vs Tsitsipas match, I don't really see what Tsitsipas has to offer Novak. All Zverev had going for him was that big serve, and Tsitsipas struggled to close it out, getting into long rallies with a guy who can't hit with the precision of Novak and definitely can't move as well. A lot of short balls Tsitsipas was playing would be absolutely punished by Novak (as well as Rafa and Fed)
To be fair, that's the only time I've seen Tsitsipas play, not sure if he's the real deal and was just finding a solution to a problem, but he got it done in the end. Hopefully it's not a blowout.