Grillo overcame a rough start with seven birdies and was three shots better than anyone else from the morning side of the draw, which proved to be the tougher. Fitzpatrick played bogey-free in warmer afternoon temperatures on a Bay Hill course in the best shape it has been in years.
Sam Saunders, Palmer's grandson, reached 2 under par until making a pair of 6s over the last three holes going for the green over water. He had a 74, same as Rory McIlroy.
Saunders says the tough part was seeing Palmer's cart stationed off the 16th tee.
"Just a big, big difference between the morning and this afternoon," he said.
