The brash-talking, Heisman Trophy-winning quarterback from Texas A&M entered and exited the Lucas Oil Stadium media room through a back door. He ignored the television screens around him, monitors that provided live coverage of his media availability and that had been showing his college football highlights prior to his arrival.
And it seemed Johnny Football had suddenly transformed himself into Johnny Business.
''This is a job now. There are guys' families, coaches' families and jobs and all kinds of things on the line,'' he said in a stern, deliberate voice at the NFL's scouting combine. ''For me, it won't be a hard thing to kick. I'm extremely focused on whatever organization I'll be at and really pouring my heart out trying to be football 24-7 with that team.''
What he has to prove now is that he means every word.
Since bursting onto the national stage in his Heisman-winning freshmen season, Manziel has been living large.
He's been courtside at NBA games, played golf at Pebble Beach, partied in Cabo and become a feature attraction for memorabilia hounds. He's participated in dunk contests, publicly complained about life in College Station, Texas, developed a friendship with Tom Brady and never been shy about - anything.
But in Indianapolis, none of that stuff means a thing.
Here, scouts and NFL front-office executives are treating Manziel as just another draft hopeful in the standard blue-and-green warm-up suit. They'll see how he runs, how he tests and perhaps most important, how he answers questions.
Most teams want to know whether this 21-year-old, fun-loving football star is mature enough to handle millions of dollars and live up to the tag of franchise quarterback. Friday's media availability may have been a good start.
Rather than showcasing his bravado, Manziel, at times, sounded almost apologetic for some of the things he's said and done recently.
''The main thing I wanted to portray that was more in the subplots of the article,'' he said, when asked about a story in which he seemed to warn Houston about bypassing him with the No. 1 overall pick, ''was that whatever team I do end up with, whenever I do get to that team, whenever I am in that organization, each one of those guys is now my teammate, my brother and if I'm on the field with those guys, I'm going to try to be the best football player I can be.''
Other times, he sounded almost defiant.
''I knew who I was meeting with, but I'm not sure of his official title. Something along the lines of just a counselor,'' he said when pressed about reports he was being treated for alcoholism and anger management while at Texas A&M.
When it became clear the 2012 Heisman winner measured in at 5-foot-11 3/4 inches, 207 pounds, shorter and lighter than his listed college measurements of 6-1 and 210, and shorter and lighter than many NFL teams seek in a starting quarterback, he wouldn't confirm the measurements. Instead, he explained that he more heart and passion for this sport than anyone in the draft.
Not all the news was bad for Manziel.
Though he stands about five inches shorter than Blake Bortles, another quarterback vying to wind up in Houston, Manziel came in with bigger hands - a potentially big advantage on draft weekend.
''I think it (hand size) is something that is highly underrated,'' said Arizona coach Bruce Arians, who has tutored Peyton Manning, Ben Roethlisberger and Andrew Luck among others. ''It depends on where you play. If you play in Lucas Oil, not too bad. Now, if you play in Green Bay and you struggle with controlling a football when it's cold and wet, that's a problem. That goes into the evaluation process hard.''
There's little doubt about Manziel's skills.
In 2012, he broke the SEC's single-season record for total offense (5,116 yards), became the fifth player in FBS history to throw for 3,000 yards and rush for 1,000 in one season and then set an all-bowl rushing record for a quarterback (229 yards).
After his jet-setting offseason and an NCAA investigation into autographs on memorabilia, critics contended a distracted Manziel regressed. But he actually threw for more yards (4,116), more touchdowns (37) and wound up with a better passing efficiency (172.9) in 2013 than he did in 2012.
The Texas native believes he will only continue to get better on a bigger stage.
But what scouts and team executives must determine between now and May's draft is whether Johnny Football is for real or whether this personality change is just one more part of his ongoing act.
''I'm from a small town of Kerrville, Texas, 20,000 people. That gets lost when people make me out to be a big Hollywood guy,'' Manziel said. ''Sometimes you get caught up in certain things, but at the same time it's about continuing to learn and continuing to adapt to everything that's going on in my life. I'm not saying it's always easy, but continuing to be who I've always been is a big thing for me.''