Nadal's serve this tournament is being majorly overrated. The Down the T serve on the ad side is non existent (as in he barely even goes for it) and the percentage isn't good.
That said, the rest of his game looks pretty off the charts this match, but this is a pretty favorable match-up. One major issue facing Tsitsipas is he's not able to transition from defense to offense, meaning if Nadal takes control of the point, and he mostly will, Stefanos can't turn the rally around. You're not going to beat Nadal that way. Obviously the backhand in this match-up is another pretty glaring issue.