It was a somber and shocked room, with Anthony left processing the final 20 seconds of the game -- and his two missed free throws with 8.4 seconds to go that would have sealed a seventh straight win for the Oklahoma City Thunder. Instead, Celtics forward Marcus Morris hit a 3-pointer with 1.2 seconds left, Russell Westbrook missed on a potential winner at the buzzer and Boston stole it, 100-99.

Anthony finally cracked a grin when new guy Corey Brewer walked by a whiteboard with two departure times for the team buses to the airport on it and yelped out in pleasant surprise, "There's two buses?"

With 20 seconds left Tuesday night, Anthony was on track for the proverbial game ball, after hitting back-to-back stone-cold 3s, then creating a third on an assist to Brewer with 1:53 left to put the Thunder up six. Anthony has been asked to give up more than anyone else this season, letting go of his jab-stepping isos in favor of becoming a roaming catch-and-shoot specialist. It was something he had to accept -- a word he uses often -- but a necessity for the Thunder to begin to unlock their offensive potential.

And on Tuesday, there was a payoff.

The Thunder have been rolling along, coming off maybe their top triumph of the season, a victory in Toronto on Sunday to snap the Raptors' 11-game winning streak. In Boston, it was a game of attrition against the scrappy, Kyrie Irving-less Celtics, with the team with three stars on it eventually taking over at the time it mattered. Paul George hit a 3 with 4:04 to go to put the Thunder up by two points, Anthony had his sequence and Westbrook hit some free throws with 24 seconds left. It looked like the kind of game the Thunder have worked hard to get past, the apparent in-the-bag win that they don't really show up for. They hit the on switch, made some shots and were ready to exit stage left.

After making some key plays down the stretch, Carmelo Anthony missed a pair of free throws with 8.4 seconds remaining that left the door open for the Celtics. AP Photo/Charles Krupa

"We had the game won," Anthony said. "Up two on the road, seven seconds left, having a chance to be sealed. So, the game was won."

"I try not to say, what happened? Or what should I [have done] there?" he said of his subsequent missed free throws. "At this point, it's a little too late for that. After the first one that was short, try to adjust it and shoot a little hard -- a little too hard a second time. So, it happens. I live with it. You make some. You miss some."

The focus was on Anthony, but a series of pretty straightforward events led to the collapse. Celtics forward Jayson Tatum finished a mostly uncontested layup, then Westbrook split free throws with 16.8 seconds to go to make it a five-point game. Celtics guard Terry Rozier hit a very open but also very deep 3. Then Anthony inexplicably missed twice at the line. It set up what, at that point, felt like the inevitable.

It really was just a matter of who was going to hit the game-winning 3 for the Celtics. Al Horford seemed like the most likely candidate, but after a scramble, the ball settled in Morris' hands on the right wing. A quick pump fake to clear one defender, then a launch over the outstretched hand of Steven Adams, and it was all net.

Melo beating himself up about missed free throws

"It's just a tough loss -- down the stretch, letting it slip away," George said. "But we're fine where we're at. This is a game that we understand we've just got to close it out. But we're fine. This is a team that plays well at home. ... They did a good job. ... We're fine. We're fine. We had this game and let it slip away."

It's the season in a nutshell for the Thunder: Two steps forward and one step back, with the responsibility of it all hanging almost exclusively on themselves. Even more than the free throw failures, OKC missed a heap of opportunities to extend its lead. The swings for the Thunder can be drastic from night to night -- from an effortless 132 points going up in Toronto on Sunday to what happened in Boston on Tuesday -- but that's the nature of featuring an offense with inconsistently efficient players.

It's something the Thunder thought they were past, taking a game for granted against an apparently inferior opponent. The Thunder already are in a precarious spot in the jammed Western Conference, but should they slip to an unfavorable seed, or even possibly all the way out, it's going to be entirely because of games like this. They have more "should've-wons" on the schedule than just about anybody.

Before finally taking his place in front of the whiteboard, Anthony disappeared in a back room for a few moments. With the mood in the locker room considerably lightened, as Brewer sat and joked with teammates, while Westbrook and George cracked up after watching a video of something on George's phone, Westbrook campaigned for Anthony to be let off the hook from his media responsibilities for the night.

Anthony shrugged it off, stepped up and took the responsibility.

"Usually, this game would have been iced," Anthony said. "Making those free throws, walking out of here with a big road victory, especially here in Boston, where it's always tough to win a game. It's easy to beat yourself up about it, but it happens. I'm pretty sure I'll beat myself up about it tonight. And tomorrow is a new day. You don't even need to kind of harp on it or let it linger. It happened. I had an opportunity to make two free throws. I missed them. I'm pretty sure I'll get that opportunity again."