– Elgin Cook threw two fists in the air. He tilted back his head and yelled.

For a moment, it was there. Then, just as quickly, it was gone.

Seconds after his thunderous tip dunk, a play that gave Oregon its biggest lead of the second half and sent the Ducks on their way to a 87-68 victory over Brigham Young on Thursday at Bradley Center, Cook’s facial features had reorganized themselves to the poker face he normally dons.

Then again, his 23-point, eight-rebound career performance probably expressed his emotions for him pretty effectively.

It was the first NCAA tournament game of his career, one that has taken plenty of twists and turns already. He was back in his hometown, the building where his father, former Milwaukee Bucks guard Alvin Robertson, used to play. And he was having the night of a lifetime.

“I think he enjoyed it,” Oregon coach Dana Altman said, reading through the sober stare that Cook wore immediately after. “I know his family did, which is really important for him. All the guys said how excited he was to come back to Milwaukee. Other than a smile when they announced it, I haven’t seen much other emotion. He wears his emotions pretty close to the vest.”

But it’s pretty obvious the sophomore doesn’t want the season to end. He will have another opportunity to help extend it and build on his success in the round of 32 when seventh-seeded Oregon plays second-seeded Wisconsin on Saturday.

The Badgers rolled American by 40 points Thursday, the biggest margin of victory in the NCAA tournament so far, but they will face a tougher challenge in trying to stop Oregon’s inside game. The Ducks had 36 points in the paint against BYU and could try to exploit Wisconsin’s interior as well.

Thursday, Cook went 8-for-9 from the floor, weaving his way to the basket to corral missed shots around the rim, and stepping out for jumpers. However he wanted to score, he did. It was his moment.

“It was one of those things, he got on a little roll,” Altman said. “I mean, that energy was flowing, the adrenaline was flowing and it could have been one of those days, but I sure hope it’s one of those days again tomorrow.”

It’s been a long time coming.

Cook, who played at Hamilton High School in Milwaukee, originally signed with Iowa State but ultimately decided to carve a new path.

Before his senior season of high school, he left his hometown for a prep school in Texas. After that, he spent the next season at Northwest Florida State, a junior college.

“I think I wasn’t ready to start my journey,” Cook said. “I felt like I had some improvement to do. I still have improvement to do.”

Cook has struggled with consistency in his first Division I season, averaging 6.8 points and 3.7 rebounds per game. But his athleticism and nose for rebounding gives him “tremendous upside,” Altman said, which the 6-6 forward showed off Thursday.

Stone-faced, of course.

Fellow reserve Richard Amardi can’t recall a moment where he has seen Cook seem legitimately excited. Even back in his hometown, he appears as serious as ever, although he cracked a smile when he first saw the NCAA logo on the Bradley Center floor.

But those who know him know the passion underneath.

Every so often, Cook will get frustrated when his team fails to execute a play or make a shot or grab a rebound and speak up.

The team stops and listens, Amardi said.

Cook hounded his teammates for their ticket allotments to get his family and friends to the arena, Oregon forward Mike Moser said. Ducks players described him as “really excited” for the opportunity.

After Cook’s highlight reel dunk, Amardi ran over to his teammate and punched him in the arm to elicit a response.

“I knew he was pumped, and I was pumped for him, so I hit him and I was like ‘Let’s go,’ ” Amardi said. “And he just looked at me and he was like, ‘Yeah.’

“I was like ‘Bro, keep doing what you’re doing.’ Everybody was happy for him. He just wanted to stay composed because that feeling can slip at any moment.”