Normally stoic Bulls center Nikola Vucevic was feeling it Friday.

With the Bulls leading by seven points in the fourth quarter, Vucevic called for the ball as he drifted toward the left wing. He drove to the basket, attacking Knicks center Karl-Anthony Towns off the dribble, and spun in the lane before flipping up a shot at the rim for a basket and a foul.

Vucevic stared at the packed house at the United Center, beating his chest twice as the fans chanted, ‘‘Voooch!’’

But Vucevic wasn’t done doing his part in closing out the Knicks. On the next possession, he received a pass from guard Tre Jones and found a wide-open Josh Giddey for a key layup that essentially clinched the victory.

The Bulls’ fast-paced, egalitarian approach to offense passed its first major test against a Knicks team that has dreams of a deep playoff run with a 135-125 triumph in an NBA Cup game at the United Center. The Bulls are 5-0 for the first time since the 1996-97 season and are the last remaining undefeated team in the Eastern Conference.

‘‘We understand [that] we need everybody,’’ said Vucevic, who finished with 26 points and seven rebounds. ‘‘We need multiple guys scoring [in] double figures. We don’t have that one go-to guy that can deliver for us every night.’’

The Bulls were going to learn something about themselves against the Knicks. It’s one thing to face teams who are on similar footing, but it’s another to face one that has tasted playoff success and has the kind of size that can give the Bulls trouble.

In the first half, the Bulls overwhelmed the Knicks’ defense, scoring 72 points on 59.5% shooting from the field overall and 47.6% from three-point range.

Near the end of the half, Giddey had the ball with the clock winding down. He already had scored 18 points and had just knocked down a catch-and-shoot three-pointer from the left wing. He watched as the clock dwindled to less than 10 seconds before getting a screen from forward Matas Buzelis.

The Knicks’ defense was unsure whether to switch or play drop coverage, and Giddey made them pay with a pull-up three. That gave him 21 points on his way to a career-high 32. He also had 10 rebounds and nine assists.

‘‘I’m happy here,’’ Giddey said. ‘‘Having confidence from your teammates and coaches to trust me to go out there and make plays, that’s what you need as a player.’’

The Knicks, however, responded after halftime. They slowed the game down and benefitted from the Bulls’ lack of rim protection. They used a 26-9 run in the third quarter to get themselves right back in the game.

But the Bulls absorbed the blows, leaning on the connection that has guided them to their early-season success. Coach Billy Donovan said Vucevic provided a calming force when the Bulls were trying to combat the Knicks’ run.

Despite the victory, the Bulls know these are only five games in a long season. The vibes are high, but sustaining that energy during losing streaks is when their camaraderie really will be put to the test.

‘‘There’s going to be stretches where we’re not winning five in a row and we’re losing games,’’ Giddey said. ‘‘That’s when we’ve got to come even stronger together.’’