Thiem can definitely win this, though it's unlikely. It's more likely he'll just give Nadal a tough match.
that could prove pretty damaging though, if hypothetically Nadal and Thiem have a longggg match and the winner of Del Potro/Djokovic gets through quickly.... could be a scenario where Nadal (or Thiem) are drained in the semifinal. I expect Nadal to try to come out aggressive tomorrow to prevent this but with Thiem that may not work. Certainly in the Madrid final Nadal sort of had to grind Dominic down