The Boston Celtics beat the Dallas Mavericks 107-89 in Game One of the NBA Finals at TD Garden in Boston, Massachusetts, on Thursday, to take a 1-0 lead in the series.

Both teams had key players facing old teammates. Kyrie Irving played for the Celtics between 2017 and 2019 and Kristaps Porzingis competed for the Mavericks between 2019 and 2022. Porzingis missed the Eastern Conference semifinals and Finals because of injury. He was cleared to play in Thursday's game, but off the bench instead of starting.

Porzingis became one of the best-performing Celtics by shooting 8-for-13 from the field to tally 20 points, six rebounds and three blocks in 20 minutes. The Mavericks chose to switch in guarding him and he punished them hard by making a series of jumpers over the heads of defenders much smaller than himself. His side built a 29-point lead (58-29) in the second quarter thanks in part to the momentum Porzingis helped create.

Boston's star duo, Jayson Tatum and Jaylen Brown, made key contributions to their victory on Thursday night as well. Brown had a team-high 22 points in addition to three steals and three blocks. He made all four of his field goals in the second period and shut down Irving in the third quarter with remarkable one-on-one defense.

Tatum shouldered more orchestrating duties for the Celtics in Thursday's game. Though his performance of delivering five assists at the cost of six turnovers was not pretty, he distracted a lot of the opposing club's defensive attention and set up many open shots for his teammates, especially outside the three-point line. His side knocked down 16 triples from 42 attempts, not necessarily shoot-to-kill, but much better than Dallas.

Compared to the Celtics, who were apparently better-prepared for the game, the Mavericks didn't find their rhythm until the second half. Their regular offense of having Luka Doncic and Irving set up Daniel Gafford and Dereck Lively II to finish efficiently next to the rim was neutralized by their opponents' defense of switching everything. Their poor shooting touch from downtown only encouraged the Celtics to leave role players open so they could focus on containing Doncic and Irving.

One of the Mavericks' few highlights came in the third period when Doncic scored 10 points and helped his team cut the deficit to eight points (72-64). Nonetheless, Doncic's slow movement on many occasions hinted that he was still haunted by a recent knee injury. He was also a target of attack on the defensive end. As a result, he failed to maintain his firepower through the fourth quarter.

Irving's shooting performance, 13 of 19 field goal attempts, was disastrous. The Mavericks can't afford to have him play like this if they want to reverse the situation in the NBA Finals. The series will remain at TD Garden for Game Two on Sunday.