BOSTON -- As Fred Hoiberg prepared for the first playoff game of his NBA coaching career Sunday night, a lot of thoughts raced through the 44-year-old's head.

He knew what All-Star swingman Jimmy Butler would provide. He understood that veterans Dwyane Wade, Robin Lopez and Rajon Rondo wouldn't be shaken by the playoff stage. But as any coach would have been in the same situation, Hoiberg was concerned about how the young players on his roster would respond. Would they live up to the moment or be overwhelmed by it? Bobby Portis emphatically answered that question with the best performance of his young career. Portis scored 19 points, going 8-for-10 from the field, grabbed nine rebounds and dished out three assists as the Bulls pulled off a surprising 106-102 win over the Boston Celtics in Game 1 of the Eastern Conference quarterfinals.

"He was one of our new, young guys that hasn't had any playoff experience that I wasn't worried about," Hoiberg said. "Because he's going to go out there and play with unbelievable confidence, he's going to play with swagger, he's just a kid that's going to go out there and lay it on the line. He plays with such effort and tenacity. He was hitting his shots tonight that was huge, we need every one of them. He stepped up big for us and hit clutch shots in the fourth quarter as well."

Portis' numbers will surprise the rest of the league, but it didn't come as a shock for the confident second year-player from Arkansas. Portis has always believed in himself and his ability, and that self-confidence was on full display Sunday night. There was no hesitation in his shots and no lack of energy in his hustle. Portis played the type of game he knew he would on one of the game's biggest stages.

"I didn't steal the show," he said after the game. "I just went out there and tried to play my role. Just tried to go out there and give some energy and I feel like I did that tonight."

Said Rondo: "I can't say I didn't see it coming. Bobby's a very confident player. He works extremely hard. What he's doing right now, he deserves it. He put in the work, staying humble. He always wanted to play. At the beginning of the year, he wasn't playing as much, but he stayed with it and things are happening for him."

To put Portis' game into context, his 19 points are the most by a Bulls player coming off the bench in Game 1 since Ben Gordon scored 30 in Game 1 of a first-round series against the Washington Wizards in 2005. The key for him going into Game 2 will be to find the consistency that has eluded him and the rest of the Bulls' young bench all season. Will this be a turning point for the young forward or another flash of brilliance in a season of mediocrity?

The beauty for the Bulls is Portis' star-crossed night came in a game in which Wade shot just 4-for-12 from the field. Niko Mirotic, Paul Zipser and Jerian Grant combined to go 4-for-22 from the field. The Bulls won Sunday's game while getting contributions from unexpected sources, a fact that after 14 years in the league, Wade knows very well.

"To win a series, we're going to have to," Wade said. "Obviously we're featuring Jimmy. Whenever the game slows down we're featuring Jimmy. We're going to have guys throughout the series, if we're going to win, it's going to have to be their night. One night it's going to have to be Niko. One night it might be me. One night it will have to be Rondo, and so forth ... to win a series you can't just depend on one guy.

"It has to be guys that make timely shots and then have big games like tonight. So we're not going to put that pressure [on him] and say, 'Bob, we need 8-for-10 again,' but we want him to continue to be aggressive and in the next game if he goes 2-for-10, we want him still taking the same shots. We believe in him. It's good to see young guys, especially with a lot of talk about our age with the guys with no [playoff] experience, to see one of the young guys come in and perform the way he did tonight."

The Bulls are not going to be able to win this series without more contributions from Wade and Mirotic, but they did what any underdog wants to do in the first game of any series: find a way to win.

"It was crazy," Portis said. "Going in there it was loud in the beginning. I'm like, 'Whoa,' because I was a little nervous at first. Once the game started going, I kind of settled down and it was fun being out there playing with these guys and us getting the win."