Thomas Bryant is growing into his role in the middle for the Wizards. (Jonathan Newton / The Washington Post)

OKLAHOMA CITY — The locker stall with the Rugrats backpack and $75 black hoodie — not exactly the overpriced fashion worn by most players — belonged to Thomas Bryant.

He is, after all, a 21-year-old playing in what is essentially his NBA rookie season since he spent the majority of the 2017-18 season in the G League. On Sunday night, the Oklahoma City Thunder didn’t know about Bryant’s cartoon backpack or his preference for wearing off-the-rack clothes. The opponent only knew Bryant is young and raw — a good candidate for 7-foot, 265-pound center Steven Adams to bully. Inside Chesapeake Energy Arena, the Thunder went at Bryant.

“Against a guy like Adams, you’ve got to be ready for anything,” Bryant said, then checked off his list of responsibilities during his 21 minutes in the Wizards’ 116-98 win. “He’s a very strong opponent. You try to keep him off the boards, trying to box him out and try to get rebounds as well and running down in transition to get Brad [Beal] open and get other guys open and get these buckets down there. So it takes a lot out of you. You’ve got to be mentally tough right there.”

Oklahoma City isn’t the only team to test Bryant. He’s in the midst of a challenging stretch of one-on-one battles for any big man, let alone one who has made just 24 career starts.

Bryant began this three-game road trip against Miami’s Hassan Whiteside. Then, there was Adams in Oklahoma City. And beginning Tuesday, Bryant will go against Philadelphia 76ers all-star center Joel Embiid on consecutive nights in the teams’ home-and-home match up.

“I’m realizing how important it is to get stronger because I’m going against guys [who] have been in the league for five or six years, ya know,” Bryant said. “Most guys have been working on their bodies and trying to put on weight and it makes me realize about taking things a little bit more seriously.”

So far, Bryant has fared as anyone might expect. He was outplayed by Whiteside, who scored 21 points, grabbed 18 rebounds and forced Coach Scott Brooks to turn to older, stronger backup Ian Mahinmi. Then on Sunday, the Thunder wasted little time in trying to exploit Bryant by running the offense inside.

On the first play, Bryant was behind Adams as he dunked the ball and on the next Thunder possession, a 1-5 pick-and-roll led to Russell Westbrook tossing a lob to Adams. Through less than nine minutes in the opening quarter, Adams connected on all four of his field goal attempts, including three in the direct matchup against Bryant. Overall, the Thunder scored 39 points as a team when Bryant had to defend Adams, according to NBA.com.

“Only thing I can say is those first couple of minutes,” Brooks said, “it was a learning experience for [Bryant].”

Through the growing pains against Adams, Bryant ran up and down the court with his mouth agape, sucking in oxygen. He grew tired but not weary enough to wilt. By the second half, Bryant fooled Adams with a slick up-and-under move and when the action transitioned to defense, he made sure to issue some punishment with his own 6-foot-11 frame.

“I tried to hit him first and try to never back down even if he does score,” Bryant said. “Just keep touching him as soon as he gets past half court, let him know that I’m there and make sure he knows to feel a body and just fight him as much as I can down low.”

Adams scored 10 points in the opening quarter, but only two more the rest of the game. The Wizards ended up holding Adams to eight rebounds, two fewer than his season average. A lot of the credit goes to Mahinmi, who played four more minutes than Bryant. His presence deterred the Thunder from rebounds and easy interior buckets. Mahinmi led the team with 10 rebounds as the Wizards thoroughly outmuscled the Thunder under the glass for a plus-15 margin.

Even so, Bryant finished with 14 points, seven rebounds and the admiration from his coach for maturing through the matchup.

“I saw growth throughout the game. He came back and played much better,” Brooks said. “And Steven does that with everybody. The guy is the strongest, most physical guy in the league … We did a good job of keeping them off the glass and I thought T.B. really grew up the last couple of games, playing against two very physical centers. He’s going to have to do it again the next two nights with Embiid.”

The NBA pro with the Rugrats backpack is indeed growing up. Burgers and fries no longer make up the bottom of his food pyramid, as Bryant transitions his diet. He’s eating more chicken sandwiches and salads and trying to be more healthy — but don’t expect him to be as hardcore as veteran teammate Jeff Green.

“He’s so healthy,” Bryant said of Green. “If I try to do that, then I’ll relapse and go right back to fried food and everything.”

The change in diet is just another step in his NBA development. He has time to work on eating healthier, but this current stretch of big-time matchups has compelled Bryant to grow up quickly on the court.

“It’s all being locked in,” Bryant said. “Just realizing the challenge that’s ahead of you and trying to see how to slow them down and just picking and choosing your battles with them.”

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