Johnny Manziel with Browns for OTAs

CLEVELAND -- Johnny Manziel is back at work after a holiday weekend in Las Vegas. And when you're Johnny Football, what happens in Vegas doesn't necessarily stay in Vegas.

The Browns' celebrated rookie quarterback reported for organized team activities Tuesday following a few days in Vegas, where he kicked off his summer by hanging poolside with New England Patriots tight end Rob Gronkowski, attending a UFC fight and being captured on video spraying champagne on patrons in a nightclub.

And, according to Manziel, he found time to study his new playbook.

Following his first practices with Cleveland's veterans last week, Manziel took advantage of a break in the workouts to head to Nevada. On Saturday, a photo of him and Gronkowski, surrounded by other partiers, appeared on several social media sites. Later, Manziel posted a photo on his Twitter account of him standing with UFC president Dana White along with a thank-you note.

Incredible fight can't thank you enough @danawhite @lorenzofertitta and congrats to @TJDillashaw #UFC173 pic.twitter.com/kRKMPq4uji

- Johnny Manziel (@JManziel2) May 25, 2014Although this was all done on his free time, and Manziel didn't commit a crime or have any known issues, his actions raised eyebrows in some circles about his commitment to football. He seemed to fire back at any criticism by posting a photo on his Instagram account Monday night of his Browns playbook and iPad with the caption: "Guess it's impossible to enjoy the weekend and study?"

Manziel, who was selected with the 22nd overall pick by the Browns in this month's draft, is expected to challenge Brian Hoyer for the starting job. Last week, first-year coach Mike Pettine said Manziel was having typical problems for a young player.

"It's like any other rookie, that he's just inconsistent," Pettine said. "I think a lot of it's the mental part of it. He's more worried about getting the formation right, making sure the motion is correct, and he's got the cadence. Then he's got to worry about where guys are. Being good mechanically takes a back seat to learning the system first. I think you see over the maturation process, once all that stuff becomes second nature, that he'll be a lot more comfortable."

Manziel has made a favorable impression with the Browns in his first weeks as a pro. He has said all the right things during two media availabilities, echoing the team's stance that he is a backup and will have to earn a starting job.

Pettine also said Manziel has shown humility, fitting in nicely with some teammates who may have expected Johnny Football to act differently.

"He's quiet, actually," Pettine said. "He's a good guy to be around. I think the guys in the locker room will be able to tell you that he's a fun guy. But you can tell, when it's time to work, he works, and he's very serious about this. You can tell he's very competitive."

Cleveland's practice Wednesday is open to the media.

The Associated Press contributed to this report.