Green lineup not two good

Horford, Smart out vs. Clippers

LOS ANGELES — The Celtics were without two key players last night — one as a precaution, one with some measure of mystery.

While Al Horford checked out well and didn’t suffer a concussion in a last-minute collision in Tuesday’s loss to the Lakers, Marcus Smart was unable to play after lacerating his hand on glass at the hotel yesterday afternoon.

“I don’t know the full story,” coach Brad Stevens said 90 minutes before tipoff against the Clippers. “We’re learning more about that. Mike Zarren (assistant general manager) and Brian Dolan (physical therapist) were with him at the hospital two hours ago (when he) got stitches. It doesn’t sound like a long-term injury, but we’re doing more research on how it happened.”

The coach explained the research as, “Obviously I want to make sure that I’m thorough in telling you how it happened and what happened. But, again, I think that he cut his hand in the hotel on glass sometime this afternoon.”

Horford’s situation was more clear at the time.

“He was looked at by the Lakers team physicians (Tuesday) night,” Stevens said. “(They) determined at the time that they did not think he had a concussion, but we’re going to just observe him tonight. He’ll be out tonight. We just want to make sure, and make sure he’s symptom-free before letting him get back out on the court. And I think that obviously having one earlier in the year and having one last year, I think it’s the right move.

“We’ve talked before that sometimes these symptoms appear after a certain amount of time, so again, I think it’s the prudent, right thing to do.

“Their doctors went through the tests and everything else, and that was what was communicated to me this morning. So it was more of a, ‘Let’s make sure before we put him back out on the court.’ ”

Said Horford: “I’m not where I need to be to play, but I’m doing all right.”

He described the feeling as “just head pressure. From dealing with this before, it’s just hard to describe. I just don’t feel right . ... Our team doctor, due to my history recently with a couple concussions, we just want to play it on the safe side. I felt good through most of everything (with the tests), but he feels strongly about me not doing anything physical today.”

As for why he came to the arena, Horford said, “What I want to do is I want to be playing. Since I’m not, at least I’m here with the guys and supporting them.”

Doc plans visit

The Clippers are scheduled to be at the Garden on Feb. 14, but, at least personally, Doc Rivers is hoping to beat that date. He’s hoping to make it to Boston a few days earlier for the retirement of Paul Pierce’s No. 34.

“We’re looking at it,” said the former Celtics coach and current Clippers leader. “We’re going to try to do it if we can. It looks like it will be possible. We’ve just got to figure out if we can or not.”

The itinerary does break right for the Clippers. They have a back-to-back in Detroit and Philadelphia Friday and Saturday, then will have an off day before taking on the Nets in Brooklyn Monday. In other words, there’s a better than average chance you’ll see Doc among the Pierce revelers.

“Oh, it’s important for me,” Rivers said. “We knew it was going to happen, obviously, and it’s so welldeserved. Paul is part of my life, and I’m part of his life — for the rest of our lives. So if I can be there, I will be.”

Rivers still keeps an eye on the Celtics when he can, but he had to turn away from the season opener when Gordon Hayward fractured his left ankle.

“That was heartbreaking,” he said. “That was awful. I couldn’t watch the rest of the game. It was just awful. First night, first play, big season, and then you see that. It just was awful to see.

“I felt terrible for Gordon. I felt bad for everybody, because you don’t want to see that ever. But, listen, they’ve had a hell of a year and they’re going to continue having it. Kyrie (Irving) has played just unreal basketball for them, and they’ve done a lot of good things as an organization to get here. (Jayson) Tatum has been great, and Marcus Smart... . You know, Marcus Smart gets a lot of flak, but, to me, he’s a lifeline. His defense and toughness lends out to the entire team. I love watching him play.

“Just overall they’ve had an unbelievable year. No one’s had more injuries than us, I guess, but they’ve had a lot of injuries. They’ve had them to key guys.”

Brown, Tatum on rise

Jaylen Brown and Tatum were selected to the U.S. roster for the Rising Stars game to be held during NBA All-Star weekend.