Guarding Zion Williamson isn’t the only challenging task occupying Zeke Nnaji’s time.

When the Nuggets’ 24-year-old big man isn’t trying to stay in front of one of league’s most powerful forwards, he’s trying to master the theme song from Hayao Miyazaki’s 2004 film “Howl’s Moving Castle” on the piano.

“It’s a great melody. It’s really fun, because the bottom hand is bouncing back and forth, and the top hand is doing its own little thing. It sounds amazing when it’s played together,” Nnaji said Monday night in the Nuggets’ locker room.

“I’ve literally been obsessed with trying to learn it as soon as possible. There’s nothing more satisfying than learning a piece and be able to play it start to finish.”

Shutting down Williamson should come close. Nnaji started for the first time this season in Monday’s 125-113 win over Williamson’s Pelicans, as Denver was without Aaron Gordon (calf injury management), Peyton Watson (knee sprain) and Russell Westbrook (hamstring strain). Nnaji said he was told at Denver’s walkthrough to prepare to start and have his minutes mirror Williamson’s.

“I watched a lot of film before the game today,” Nnaji said. “I felt like I was really locked in on everyone and what their tendencies were. I felt good about going out there and being able to guard.”

Williamson didn’t score in the first quarter and tallied six of his 14 points in the final 5 minutes. Nuggets coach Michael Malone had an easy choice for his defensive player of the game for a second straight game.

“When you guard a great player, a forceful player like that, you have to attack that matchup and not be afraid of it,” Malone said. “I felt Zeke went out there and embraced that challenge from opening tip all the way until the end.”

Williamson needed 13 shots to get there. Milwaukee star Giannis Antetokounmpo is the only player in the league who averages more points in the paint per game than Williamson.

“He loves to get to the rim. He loves to get to the cup. He’s an amazing player,” Nnaji said.

“Being able to play that drive and know that that’s what he’s trying to get to, that’s one of the biggest things.”

Nnaji scored a season-high 12 points and did so on nine shots. He grabbed five rebounds and blocked a shot in 31 minutes of playing time, three shy of matching his career high. He also hit his first two 3-pointers of the season. The first one got the Nuggets on the board, and the second one put Denver up 14 in the final 90 seconds. Michael Porter Jr. provided the assist on Nnaji’s dagger.

“Because of my situation and my injury past, I’ve had to work extremely hard, but Zeke, this year, may have taken the crown as the hardest-working player on the team, because, regardless if he plays or not, every single game, whether it’s home or away, he’s probably on the court for 30, 40 minutes. Every day on the road, when we get into cities, he’s going back and finding a gym at night. It doesn’t matter if he plays. It doesn’t matter if he has a bad game,” Porter said.

“He’s been consistent.”

Nikola Jokic agreed that Nnaji’s work ethic has been second to none among the Nuggets.

“He’s in the gym. He’s in the weight room, staying late, coming in on off days. I think he’s the guy who is probably working out the most from us,” Jokic said. “I think he deserved the chance, and he showed that he can play.”

Jokic also said the Nuggets don’t need to make any moves ahead of Thursday’s trade deadline to accomplish their goals this season. Malone and Porter made it sound like Porter would be around for the foreseeable future. If the Nuggets don’t move Jokic or Porter, Nnaji’s $8.9 million contract is the most expensive contract the team can move. He’s not sweating the deadline.

“I’m not going to lie. I’m not focused on that,” Nnaji said. “I’m just worried about … I’m playing right now, so I’m trying to help us get a win. If anything happens, then it happens, but right now, I’m in the present.”

That means another matchup with Williamson and the Pelicans on Wednesday. More time on the piano bench practicing “Merry-Go-Round of Life,” the film’s theme song that was originally composed by Joe Hisaishi, is also an important part of his preparation.

“It’s really meditative for me. I can just go out there on the keys and let loose,” Nnaji said. “No matter what is going on in my life, on the court or off the court, I can go and just let loose, express myself through music and it feels amazing. It’s something I need to do every day.”