LOS ANGELES (AFP) — Pascal Siakam drilled the game-winning three-pointer in overtime as the Indiana Pacers beat Boston 135-132 on Wednesday, handing the National Basketball Association (NBA) champion Celtics their first defeat of the season.

Indiana’s victory in a rematch of last season’s Eastern Conference finals left the Cleveland Cavaliers as the East’s only unbeaten team.

The Cavs gave the Los Angeles Lakers a rough ride, despite a warm reception for Bronny James in Cleveland, where the hosts dominated in a 134-110 victory to improve to 5-0.

In Indianapolis, Bennedict Mathurin led the Pacers with 30 points and 11 rebounds. Siakam added 29 and Tyrese Haliburton scored 17 points with 12 assists for Indiana, who led by as many as 24 early in the third quarter.

Boston outscored Indiana 38-24 in the fourth, twice cutting the deficit to three before Jayson Tatum drained a step-back three-pointer with 14.4 seconds remaining in regulation.

Boston took their first lead since the first quarter on Derrick White’s driving layup that made it 132-130 with 39.7 seconds left.

But Siakam had the last word, making a basket to tie it then rising for a three-pointer over Haliburton with 7.3 seconds to play.

“It’s big, it’s big,” Siakam said.

“We got a couple of games where we lost by a couple of turnovers, rebounds. So we wanted to get this one.”

Tatum scored 37 points, Brown added 25 and White scored 23 for Boston, but they couldn’t pull off the miracle.

“We let them come back, but I thought we fought,” Siakam said.

“That’s what we’ve got to do. We’ve got to be a team that fights to the end.”

Boston dropped to 4-1 as Cleveland improved to 5-0 for just the third time in franchise history.

Wednesday’s game was billed as a homecoming for LeBron and Bronny James — who hadn’t played since he was subbed in to play alongside his superstar father in the Lakers’ season-opening victory over the Minnesota Timberwolves.

That made them the first father-son duo to play alongside each other in an NBA game.

This time around, LeBron James had departed for good and the game was out of hand when Bronny James was subbed in late in the fourth quarter — to cheers from Cleveland fans who remember him as a toddler attending Cavs games when his father starred for his hometown team.

Although the 20-year-old drafted by the Lakers in June is expected to be headed to the developmental G League soon, he did hit a mid-range jump shot for his first NBA points.