Marcus Smart was absolutely convinced his buzzer-beating attempt had landed but felt the Boston Celtics paid the price for a slow start in their defeat to the Sacramento Kings.

The Celtics guard went to the hoop with a last-gasp effort that seemed destined to land but hit the rim and trickled to safety as Boston saw a 10-match winning streak in the NBA snapped in a 100-99 reverse.

It capped a difficult evening for Smart, who went two-for-16 from the floor and made just one of eight three-point attempts.

Speaking about the late near miss, he said: "I thought it was going in.

"I think everybody thought it was going in and it just rolled out. It's one of those games, but that's not what lost us the game. 

"What lost us the game was the early start for me and everybody else in that starting unit. We allowed those guys to get very, very comfortable, and as we know in this league, especially with great guys like those are over there, when they get comfortable it's kind of hard to get a stop to get going."

Prior to that moment, Smart opted to shoot with 15 seconds remaining, having earned an offensive rebound and missed.

"I came up with the offensive rebound, and instead of kicking it back out I lost track of time," he added. 

"I thought I had a quick layup, instead of kicking it out and letting them foul us and controlling the game. And then I got called for the foul. He made two big free throws and got the bounce on one of them to go in.

"And then Kemba [Walker] made a great play. They stopped him, my man turned around to help and he kicked it. I drove it, just like anybody else would do. The ball felt like it sat on the rim forever."

Coach Brad Stevens hopes his side can learn from the mistakes they made.

"There were a lot of controllables that we missed, but they had to also make some incredible shots," Stevens said. 

"So, I think it was a mixture of those two, and we'll get to work from a film standpoint on those controllables and hopefully be better in those scenarios tomorrow. 

"But also credit them. I thought a couple of those shots were awfully well contested and those go in and it makes a big difference."