Simon, who has spent more than four hours more than Murray on court during the tournament, said that his elbow was a particular worry for him.
"I will need to recover from this one before I think about Andy," said Simon. "I was almost dying after the end of the second set."
Asked which part of his body was in most pain, he replied: "Everywhere, that was the problem.
"[My elbow] was cramping every time I was trying to play fast so I was just trying to find my rhythm and just trying to make him work."
Simon last beat Murray at the Rome Masters in 2007.