The Celtics’ at full strength, with the most talented starting five in the NBA, looked nearly unbeatable through the first two months of the season. But even the best can’t be perfect every night.

On a night that they looked mostly out of sorts, the Celtics found a way to make things interesting in the final minute after a furious fourth-quarter comeback. But it was too little, too late in a 127-121 loss to the surging Thunder in Oklahoma City, snapping the Celtics’ six-game winning streak.

Kristaps Porzingis scored 34 points and Jayson Tatum added 30, but Jaylen Brown went just 4-for-17 on a bad shooting night. The Celtics’ defense wasn’t nearly good enough. A poor third quarter – in which they let the Thunder score 40 points – was ultimately their downfall. The Celtics had no answers for Shai Gilgeous Alexander, who erupted for 36 points. When they made a few runs late, the Thunder had every answer.

The Celtics are now 15-2 when at full strength this season, with the losses coming to the 76ers and now the Thunder, who are surprising the NBA with the second-best record in the Western Conference.

The C’s really had no business making this a one-possession game in the final minute. The Thunder had their way with them in the third quarter. Josh Giddey was unusually hot from 3-point distance. Gilgeous-Alexander got everything he wanted and the Thunder were dominating the Celtics in the paint.

It seemed like the game was over within the first two minutes of the fourth. With Gilgeous-Alexander and rookie sensation Chet Holmgren on the bench, the Thunder pushed their lead to 16 with a Cason Wallace 3-pointer. But despite going down by 18, the Celtics did not quit. Though they were being thoroughly outplayed for most of the night, it still seemed like they had one run in them.

Derrick White ignited a 10-2 run that cut the Celtics’ deficit to eight when he found Tatum for an alley-oop with 5:09 to go. Holmgren responded with a back-breaking triple, but the Celtics kept pushing. The cut it to six with 2:28 to go when Brown was fouled hard on a dunk attempt and made two free throws. Holmgren replied with another 3-pointer, but Porzingis’ three-point lead cut it back to six.

The Celtics trailed by seven with 1:19 to go, but after two Tatum free throws and a defensive stop, White drained a ridiculous rainbow 3-pointer from the corner to cut Oklahoma City’s lead to two with 41 seconds left. But the C’s couldn’t get a stop when they needed one, as Jalen Williams attacked Tatum in the paint and made a floater to restore the lead to four.

Porzingis was fouled with 15 seconds left and made two free throws before Giddey hit two free throws with 12 seconds left. On the ensuing possession, Tatum found Porzingis wide open in the corner and hit what appeared to be a 3-pointer to cut the deficit to one. But even though he took a moment to set himself before shooting it, it was ruled Porzingis’ toe was on the line for a two-pointer. Two Gilgeous-Alexander free throws with three seconds to go sealed it.

Other notes and takeaways:

– White left the game with 5:20 remaining in the first quarter after bumping heads with Gilgeous-Alexander as he started bleeding above his left eye. In another example of the guard’s value, the C’s trailed by as many as nine before he returned with 8:30 remaining in the second. According to NBC Sports Boston’s Abby Chin, White needed four stitches and glue to repair the cut above his eye.

It was probably no coincidence that the Celtics immediately went on a 9-1 run to tie the game upon White’s return.

– That run was spurred by Porzingis, who had a massive first half. With the Celtics trailing 41-34, he produced back-to-back blocks, both leading to Brown pushing the pace in transition and getting fouled both times. At 41-38, White interrupted an alley-oop attempt by the Thunder in transition, and that led to Payton Pritchard’s game-tying 3-pointer from the corner.

Porzingis had a highly effective first half. With Tatum and Brown having slow starts, the big man scored 18 points on 7-for-9 shooting to keep the Celtics hanging around. Then, after Tatum and Brown started the game a combined 1-for-9 from the field, the duo combined to score 11 points over the final 2:30 of the second to give the Celtics a 61-58 halftime lead.