JAYSON TATUM AND Marcus Smart each scored 21 points to lead the Boston Celtics over defending champion Toronto 112-94 in Sunday’s opening game of their second-round NBA playoff series.

Kemba Walker added 18 points and 10 assists for the Celtics, who also had 17 points from Jaylen Brown plus 13 points and 15 rebounds from Daniel Theis.

“Marcus today was unbelievable on both ends,” Celtics coach Brad Stevens said. “All our guys played with great purpose, great enthusiasm. We just have to clean some stuff up.”

Game two of the best-of-seven Eastern Conference series comes Tuesday in the spectator-free COVID-19 quarantine bubble at Disney World in Orlando, Florida.

“We just need to follow the game plan and play with purpose and compete and that’s what we did,” Tatum said. “They are not going to give up. Every game is going to be a dogfight.”

Boston frustrated Toronto shooters, the Raptors going 31-of-84 from the floor and 10-of-40 from 3-point range — the most 3-point misses ever by Toronto in a playoff contest.

“We just didn’t play well enough to win,” said guard Kyle Lowry, who led Toronto with 17 points despite a sore left ankle. “We’ve got to do our coverages harder, execute better.”

In the Western Conference, the Los Angeles Clippers advanced to the second round by defeating Dallas 111-97, capturing their series 4-2.

Kawhi Leonard, last year’s NBA Finals Most Valuable Player while with the Raptors, sparked the Clippers with 33 points, 14 rebounds, seven assists and five steals.

“Just got to my spots and put up the shot with confidence and it went in,” Leonard said after his fifth 30-point game in a row. “Just kept giving it to me and it went in with confidence.”

Luka Doncic scored 38 points in a losing cause as the Clippers opened the second half with a 20-3 run for a 77-54 edge, saw the lead trimmed to 88-82 early in the fourth in a Doncic-led fightback only to pull away again down the stretch.

“Momentum, it can switch real easily,” Leonard said. “You have to keep fighting when you’re up and when you’re down stay focused.”

A later Western Conference game six pits the Utah Jazz against Denver with the Nuggets facing elimination trailing the series 3-2. The series winner will face the Clippers next.

The games were the first for each club since last Sunday after a walkout shut down the NBA playoffs for three days until team owners and players agreed on league measures to support voting, social justice and racial equality programs.

“We needed a chance to catch our breath as players and black men and get some things handled. It was a really emotional week. It was up and down. It was hard,” Lowry said.

“Basketball always matters but in this situation, in this time, it’s taking a back seat. We’re going to perform at the highest level we can perform at, no excuses, but we have an obligation because we have this platform and can reach out to the world.”

- Raptors eyed going home - 

Raptors players said they would have walked away without concrete measures from the NBA.

“We were seriously, and I think all players, were seriously considering leaving,” Lowry said. “Our job is to play basketball but it’s also to speak out. We’ve got to do both. I take pride in that. It’s a hard job.”

Toronto’s Cameroonian playmaker Pascal Siakam agreed, saying, “There was a debate, leave here or stay here. If we’re going to stay, we have to get with it.”

When it came to walking out, Toronto’s Serge Ibaka said the Raptors “were very close. As a group we figured everything out and we stayed.”

Boston’s Jayson Tatum said the playoff shutdown, and support from other leagues, made a clear point.

“The world has seen how powerful we are as a collective, has seen the things we can accomplish when we all come together as one,” he said.

- ‘They had more energy’ - 

Smart had 10 points and Brown nine in the first quarter as the Celtics seized a 39-23 advantage.

“I got a great look off the first one and kept it going the rest of the night,” Smart said.

The Raptors pulled within nine in the second quarter but the Celtics stretched the lead beyond 20 points early in the third quarter and stayed in command to the finish.

“Overall they had more energy than us,” Siakam said. “They were more active than us.”

The Celtics were without Gordon Hayward, who is out until late September with a right ankle injury.

“We’re not going to replace him with one person,” Stevens said. “We’re going to do it by committee. We’re going to play to our strengths.”