Though he completed the ride, Thomas made it clear he has some work to do in order to keep up with his peers and may quit competing against the No. 1 player in the world altogether.
"Boys, I'm not going to sugar coat it, kicked my ass trying to keep up with y'all," Thomas said on his Instagram. "Rory, I don't really want to do this with you anymore. You're not that fun."
McIlroy posted on his own Instagram account that he set a personal record during Friday's workout.
The Northern Irishman wasn't the only one who pushed Thomas, either.
"Charley Hoffman impressed me a little bit, not going to lie. Well done," Thomas continued. "Commissioner Jay (Monahan), thank you also for kicking my ass. Really made me feel good about myself."
Bubba Watson initiated the group ride Friday and might be Thomas' only competition moving forward.
"Bubba, maybe you and I need to start having classes together. That was rough, bro," Thomas concluded.