Celtics coach Doc Rivers speaks to the media following the Celtics’ 109-104 loss to the Thunder at TD Garden.

WALTHAM — For the second time in three days, Paul Pierce injured his right shoulder. This time, the injury happened midway through Celtics practice when he ran into a back screen and fell to the ground. Rivers said trainer Ed Lacerte said if it’s just a stinger, Pierce should be fine to play.

“He actually got hurt again,” Rivers said. “It’s a stinger. It was the same exact reaction. It looked worse today. Eddie said if it’s a stinger, he’ll be fine but you get concerned because it’s a game and a practice, exact same thing.”

“That’s something you play a guy five minutes and that can happen, Rivers added. “There’s nothing you can do about that. The good news is it’s not a shoulder separation or anything and probably the worst case is he misses a game or two, at worse. That’s not all bad and obviously, you’d like to have him and it’s not a lower body injury.”

Meanwhile, Kendrick Perkins, who has missed the last two games with left knee tendinitis, is expected to return to the starting lineup on Wednesday night against Kevin Durant and Oklahoma City at TD Garden.

Doc Rivers remember playing for Gregg Popovich in San Antonio. But not how you might think.

Rivers was the point guard for the Spurs between 1994-96 when Popovich was the general manager.

Then Rivers retired the season before the Popovich fired Bob Hill for a 3-16 start and took over as head coach.

Four NBA titles later, the man with the second-longest head coaching tenure in the NBA is the envy of the league – including Doc Rivers.

“Well, he’s earned it,” Rivers said of Popovich’s tenure. “Pop’s been phenomenal. He’s not only been a coach but he a built a whole program. San Antonio has always been very good. They just could never get over the hump. When I played there, we made it to the Western Finals against Houston and they had been there before.

“Pop came in and not only took them back there, but took them over that and he did in the right way with character players. The organization is first class and no one would have thought 10 years ago that San Antonio would be the organization that most of the league, and not just in basketball, would model their teams after and they do.”

So it’s no surprise that after titles in 1999, 2003, 2005 and 2007, the Spurs have the kind of resume that others in the league want to copy – even the mightiest of all NBA dynasties with 17 banners already hanging in the rafters.

“Well, we would like to be,” Rivers said of the desire to copy the Spurs’ way. “And that’s what we want to be because they’ve been consistent with it and have done a great job with it. Everyone has their own way but there are a lot of things that I do as a coach and there are a lot of things we do as an organization that we got from them.”

Celtics coach Doc Rivers made his weekly appearance on the Dennis & Callahan show Thursday morning to talk about the state of the Celtics. “We’re closer,” Rivers said. “I don’t think anybody can say they’re there right now as a team.”

Rivers said the Celtics’ recent improved play can directly be attributed to the team’s improved health. “We were 23-5 [to start the season], we were completely healthy,” he said. “I felt this throughout that whole streak. It’s amazing how conveniently everybody forgot about that. … So many different guys had to play so many different roles. … That took a toll on us.”

Rivers said he’s focused on continuing to get the team in rhythm the rest of the regular season, but, “I still want to get them rest as well.”

Rivers was asked about the NCAA tournament and which underdog he thinks has the best chance of advancing. “I think Cornell’s the best [underdog] that’s still available,” Rivers said. “Unfortunately, they have to play the best team [Kentucky]. … If that game is close, I think Cornell wins that game.”

Rivers said he has been getting grief from Nate Robinson since Robinson’s alma mater, Washington, knocked off Rivers’ school, Marquette, in the tournament’s opening round. “I’m still getting [teased],” Rivers said. “Every time he walks by me, he sings the Washington fight song.”

To hear the interview, click on the Dennis & Callahan audio on demand page.

BOSTON — Doc Rivers speaks to the media following the Celtics 113-99 win over the Denver Nuggets.

Doc Rivers talks to the media following the Celtics win against the Knicks on St. Patricks Day.

Following their loss to the Cavaliers on Sunday, the leadership of the Celtics came into question. As in, where is it coming from?

Ray Allen says the Celtics don’t come down to one or two individuals. They are not led by a single player, he notes. Never have been nor do they plan on becoming so.

“The same as it’s always been,” he said prior to the Celtics – Pistons game on Monday. “We’ve got a bunch of leaders on this team.”

Kendrick Perkins offered a remedy to help the Celtics on Sunday after LeBron James led the Cavs to victory.

“I think maybe a different guy gotta try to step up and be a leader,“ reported the Boston Globe. “I think sometimes you try to feed off your All-Stars, but maybe somebody else gotta step up. I’m talking about leading by example. One spark or positive energy on the court and guys tend to feed off that. Maybe it’s gotta be me, Rondo, ’Sheed, somebody.’’

A day later, Doc Rivers echoed the notion of players needing to step up. He believes his players have it in them, it is just a matter of putting it out there on the court. He pointed out Rasheed Wallace and Marquis Daniels specifically as two players the Celtics need better production from.

“I don’t care how frustrating it gets for me,” Rivers said before Monday’s game. “I see it, and if you see it or not, I see it and I’m going to get it out of you. And that’s what I told them after the game [Sunday]. I don’t know how but I will get it out of you.”