Jack had 22 points, a career-high nine rebounds and eight assists and Portland won without the suspended Randolph, 93-83 over the Toronto Raptors on Sunday.
Martell Webster added 22 points and eight rebounds for the Trail Blazers, who won for just the second time in nine games.
Randolph made an obscene gesture to Pacers fans in Indiana on Friday and Blazers management responded by suspending him for one game and fining him. LaMarcus Aldridge, the No. 2 pick in the draft, started in place of Randolph and had three points and three rebounds.
Jack said with a smile that his teammates didn't tell him early enough that he was close to a triple double.
"They didn't tell me that I needed two assists and a rebound until maybe a minute to go. It's kind of tough to try to get it, but I'm more than happy with the win," Jack said.
Portland coach Nate McMillan met with Jack before the game and told him he didn't want anybody trying to match what Randolph does.
"I talked to him about leadership. With Zach not being here today we really needed him to take control and take over as a leader," McMillan said. "He was the guy who set the tone for us from the start."
Jack called his performance terrible after he had five turnovers and just six points in Friday's loss. He rebounded against Toronto -- making his first seven shots and finishing 9-for-15 from the field. The second-year point guard had 30 points and 10 assists in a victory over Milwaukee on Wednesday before struggling against Indiana.
"He played great and he's been great. He's making a name for himself in this league," Webster said.
Toronto All-Star Chris Bosh missed Sunday's game and will miss two more games because of a bruised left knee. Bosh did not make the trip to Florida, where the Raptors play in Miami on Monday night and in Orlando on Wednesday night.
Andrea Bargnani, the No. 1 pick in the draft, replaced Bosh and had eight points and three rebounds in his first start.
Morris Peterson had 23 points for the Raptors, who were outrebounded 56-34 without Bosh, who's third in the NBA in rebounding.
"We couldn't rebound," Toronto coach Sam Mitchell said.
The Raptors, who have lost three straight, lacked energy and shot just 35 percent.
"This was a game we should have won. We should have come out and had more energy," Toronto point guard T.J. Ford said. "They just outplayed us and outworked us."
Fans booed after Portland's Jamaal Magloire made two free throws to give the Trail Blazers a 15-point lead with just over four minutes left.
Toronto cut the lead to seven with less than two minutes left, but Juan Dixon made two free throws with 52.1 seconds remaining. Peterson followed with a 22-foot-jumper with 47.8 seconds left, but Webster made two more from the line.
After Toronto's T.J. Ford made a 3-pointer, Jack made two free throws to make it 91-83 with 41 seconds left.
Dixon finished with 16 points.
Jack scored 12 points in the first quarter and Webster had 11 in the second quarter as Portland led 50-41 at halftime.
- Bosh injured the knee in Friday's game in Chicago and it swelled up on Saturday. Bosh is averaging 20.5 points and 12.2 rebounds, but has been bothered by a variety of injuries this season.
- Identical twins Joey and Stephen Graham went scoreless. Joey played seven minutes for Toronto while Stephen played three minutes for Portland.
- Bargnani returned after missing Friday's game with a sore back.