Correct me if I am wrong, but my understanding is that Khedira is over his injury but would be well short of match fitness as I don't think he has played a single minute in pre-season. Perhaps he might be available from the bench.
For the game against Fiorentina, I think we only have Lemina, Pjanic, Asamoah & Hernanes available. Khedira is short of match fitness, Sturaro & Marchisio is still injured and Pereyra is basically going to be sold before the weekend. It looks like the midfield 3 balotaggio would be whether Hernanes starts or Lemina starts. Asamoah and Pjanic are probably the only definite starters.