Danilo Gallinari took an inbounds pass with 5.3 seconds left before passing to Williams, who drilled a 28-foot 3-pointer over a defender while fading to his left to give the Clippers a thrilling 119-116 win over the Nets and set off a jubilant celebration at Staples Center.
It was the first buzzer-beating winner Williams had hit in his 14 seasons, according to ESPN Stats & Information. The NBA's all-time leading bench scorer celebrated by sprinting to the far corner of the court, where he stood with his arms raised as he was mobbed by his teammates.
"I get made fun of that I don't know how to celebrate," Williams said after scoring 25 points to help the Clippers win for the seventh time in eight games. "My teammates say I don't know how to celebrate. I've been working on my [celebrations]. They say I don't show emotion."
The Clippers and Nets are fighting for a playoff spot in their respective conferences, and they both played like a berth was at stake in a game filled with emotion and wild momentum swings. The Clippers (41-30), winners of seven of their last eight, are eighth in the West but only two games out of the fourth spot. The Nets (36-36) have lost three straight and are seventh in the Eastern Conference, 1.5 games behind Detroit.
The Clippers trailed by as many as 19 in the second quarter, only to storm back and take a 60-55 lead into the half following a 33-9 run. They led 105-91 with 7:07 left and then 116-106 with 1:02 left to play before the Nets scored 10 unanswered to tie the game with 5.3 seconds left.
But Williams, who passed Dell Curry last week for most points scored by a reserve in NBA history, would not let the game go to overtime as he continued to show why he is the league's premier sixth man for the second straight season.
Williams is no stranger to clutch baskets. Over the last two seasons, Williams has hit three go-ahead baskets in the final five seconds, tied for the most in the NBA. But this was his first buzzer-beating winner.
"He's been amazing, absolutely amazing," Clippers coach Doc Rivers said. "He's not scared."
"He's had buzzer-beaters, but maybe there was one second left," Rivers added. "But when I guess you say buzzer-beater, I guess that means when it leaves your hand, there is no other shot. He's made some huge shots for us all year. It's nice they didn't get another opportunity because they probably would've scored, the way things were going."
Nets coach Kenny Atkinson said there was no thought about fouling Williams before the shot.
Clippers forward Montrezl Harrell knew what would happen once Williams got the ball.
"Game over," Harrell thought. "We know he is going to do something, whether he is going to either get fouled, go to the free throw line and end the game or do what he did tonight, hit a big-time shot."