Based on the Marcus Smart calendar, the Celtics had never beaten the San Antonio Spurs.

Eleven straight losses, including each of the last six seasons in the Garden, dating back to March 31, 2011. Safe to say the unsavory streak was on the mind of the Celtics guard when he talked to Kyrie Irving before last night’s game.

“I had no idea until the beginning of the game (when) Marcus told me that he hadn’t beaten the Spurs,” said Irving. “I’m glad we got that out of the way.”

This was by no means a complete San Antonio team, with Kawhi Leonard and Tony Parker both rehabbing quad injuries, and Manu Ginobili getting an early rest.

But prior to the 108-94 Celtics win — their fifth straight — San Antonio had owned the parquet. Irving changed that dynamic with a 24-point, six-assist gem, and balance continued to emerge throughout the Celtics roster, including 14 points and 13 rebounds from Al Horford, 18 points on 6-for-11 shooting from Jaylen Brown, and 12 points off the bench from Terry Rozier.

The latter also nailed this one down with a 10-point fourth quarter, including eight straight points that blew the game open.

It certainly wasn’t the kind of performance that holds up to the standard of Spurs coach Gregg Popovich, from 50 percent free throw shooting to, defensively, 47.7 percent Celtics shooting, including 35.5 percent from downtown.

The Celtics, of course, are missing a big piece and for the rest of the season, too, as Gordon Hayward recovers from a broken tibia and dislocated ankle.

But last night’s win is a sign, according to Horford, that the gelling process may be ahead of schedule.

“Yes. Yes. Once (Hayward was injured), we really didn’t know where we were at as a group,” said Horford. “But I felt like we’ve really come together and we’re trying to take it day by day, just listening to the coach, and he’s steering us the right way.”

And, in a relatively seamless process, Irving has taken the chair that Isaiah Thomas occupied at the head of the table. According to Rozier, every Celtic stepped aside to let it happen.

“He’s our leader. He’s our star. He’s our player,” said Rozier. “Things were going rough for him probably at the beginning of the season. A lot of people doubted him, but he stuck with it. He’s a professional and we learned to play with him. Him finding Al in the fourth quarter in a lot of these games, it’s just Al being in the right spot and he’ll find you. He’s not selfish. So I just feel like we adapted to him and we rolling so we just got to keep it going.

“He was just being a young 25-year-old in the world that’s seen a lot of things already, but he didn’t come here on no cockiness, none of that, and we respect him for that. He’s always talking to us and he’s just being our leader. The way he goes about things is great. We adjust to him. We adapt to him and we’re rolling right now so we just want to keep it.”

Irving accepted Rozier’s praise quietly.

“Terry’s a funny guy, I’ll tell you that. The flip side of that is I feel like I had to adjust to them. That was probably the biggest thing,” he said.

“Coming in and even playing pickup with those guys in the beginning, they have a team-oriented-at-all-times vibe and culture here. And I had to be able to adjust my individual talent to the greater good of the group. And I feel like that has been going a lot better than even I expected because of the guys that we have in this locker room. They make it easier for me to just adjust myself.

“And then on the flip side of that it’s just a new team for all of us. Every single game is a chance for us to continue to get better and depend on one another. And I feel like we’re doing a great job of that. I just, I admire all these guys’ talents.

“They know. They probably won’t tell you but I’ve been watching these guys for a long time. When Terry was at prep school and (Jaylen Brown) was in high school playing at City of Palms, and (Jayson Tatum), seeing him since junior year. I’ve studied all these guys’ games even before I came here.

“So getting a chance to play with them, it took me a few weeks to adjust. And I’m still adjusting. But they make it a lot easier for me.”