Another nail-biter saw the two-time defending champion Golden State Warriors drop a 112-109 decision to the Mavericks in Dallas.
Irving added 11 assists and Jayson Tatum chipped in 21 points and seven rebounds for the Celtics, who erased an eight-point fourth quarter deficit to improve to 9-6 while the Raptors fell to 12-4.
Warriors endured a horrendous shooting night, connecting on 42.1 per cent of their shots from the field and just 22.2 per cent from three-point range.
Presenter Takis Tsoukalas targeted Thanasis Antetokounmpo with the "racist" remark shortly after he had helped his team, Panathinaikos, beat arch-rivals Olympiakos.
Kareem Abdul-Jabbar is NBA's all-time points leader with 38,387 points, followed by Karl Malone (36,928) and Kobe Bryant (33,643) with Michael Jordan one place ahead of James at 32,292.
Orlando overturned a 16-point deficit in the final quarter to post a 111-106 win.
Warriors remain on top of the Western Conference standings with 11 wins and only three defeats.
Warriors remain on top of the West after suffering only their third loss of the season.
LeBron James dunked for the eventual winning basket and Tyson Chandler made a game-saving defensive stop in the final seconds, to lift Los Angeles Lakers to a 107-106 victory over the Atlanta Hawks.
Harrell provided that spark, coming off the bench to score 26 points on Saturday as the Clippers edged the Milwaukee Bucks 128-126 in overtime.
Joe Ingles tied his career high with 27 points to help the Utah Jazz beat the Boston Celtics.
Boston Celtics rallied from a 22-point third-quarter deficit to hand Suns a heartbreaking 116-109 overtime defeat.
Ben Simmons flirted with a triple double, finishing with 16 points, 10 rebounds and eight assists for the 76ers who were 6-0 at home and 0-5 on the road coming into Wednesday's contest.
McCollum connected on 17 of 23 attempts from the field, including five of 10 from three-point range, as the Trail Blazers improved to 8-3 and handed Giannis Antetokounmpo and the Bucks just their second defeat of the season.
The 2017 NBA MVP grimaced in pain after rolling over on his ankle as he landed on Pelicans player Anthony Davis's foot after going up for a rebound in the third quarter.