Jalen Brunson #11 of the New York Knicks dribbles the ball during the game against the Golden State Warriors on MARCH 18, 2024 at Chase Center in San Francisco, California. Noah Graham, NBAE via Getty Images/AFP 

LOS ANGELES (UPDATED) -- Jalen Brunson scored 29 points as the New York Knicks overturned a 20-point deficit to stun the Boston Celtics 108-105 in overtime in their opening NBA Eastern Conference semi-final series clash on Monday.

Brunson -- the 40-point hero of New York's series-clinching win over Detroit last week -- was once again in superb form as the Knicks silenced Boston's TD Garden with a remarkable second-half fightback.

Brunson's 29 points included five-of-nine from three-point range, with OG Anunoby also getting hot with 29 points including six three-pointers.

Jaylen Brown and Jayson Tatum led Boston's scoring with 23 points apiece.

"It was a great team win," Knicks coach Tom Thibodeau said afterwards.

"We started well, then we fell into a hole and then we fought our way out and then we made tough plays down the stretch," Thibodeau added.

Second seeds Boston, the reigning NBA champions, looked poised to get the best-of-seven series off to a winning start after pulling into a 72-52 lead early in the third quarter.

But Boston's double-digit cushion was whittled away after Anunoby and Brunson combined for 21 points in the third quarter as the Celtics scoring dried up.

Al Horford settled Boston's nerves with a three-pointer to close the quarter that left the Celtics up by nine points at 84-75.

The Knicks opened the fourth quarter though with quick three-pointers from Miles McBride and Anunoby either side of a Karl-Anthony Towns layup to close to within one point.

New York pulled level at 86-86 with just under eight minutes left in the quarter before a run of 11 points from Brunson helped New York sweep into a 97-91 lead.

Brunson had a golden chance to win it in regulation with the score tied at 100-100 but missed a layup with three seconds remaining.

Anunoby, Mikal Bridges and Towns then took over in overtime to seal a gutsy win for the Knicks.

Celtics coach Joe Mazzulla said lax defense in the second half had cost his team dearly.

"We left some of their good shooters open," Mazzulla said. "There's detail stuff that we have to be better at."

Brown, who shot only seven-of-20 from the field and made only one-of-10 attempted three-pointers, said the Celtics would not get hung up on their wayward shooting night as they prepare for game two in Boston on Wednesday.

"We had a historic night of missed three-pointers," Brown acknowledged. "We'll take a look and kind of see what the energy was.

"In reality you've got to have a short-term memory -- throw it away and get ready for game two.

"We don't have time to let stuff carry over."

© Agence France-Presse