NEW ORLEANS — Yesterday was Terry Rozier’s birthday, and he was fully expecting a call or text from Danny Ainge.

“Every year,” said the Celtics guard. “Usually he’s the first. Top five definitely.”

And fine fellow that Rozier is, he most certainly returned the wish. Though 35 years apart in age — Ainge turned 59 yesterday, Rozier 24 — they have been very much together since June 25, 2015, when the Celtics president of basketball operations accepted the wrath of fans wanting a bigger name and selected the spark out of Louisville with the 16th overall pick.

(This was, of course, after Danny tried to trade numerous picks and the Old North Church to Charlotte to cut the line and draft Justise Winslow, but that was beside the point on St. Patrick’s Day — and every other day, as well.)

“He changed my life,” said Rozier of Ainge.

The mutual admiration has gone so far as to become a regular slice of Twitter humor, with the tale going that, even on a team with the likes of Kyrie Irving, Gordon Hayward, Al Horford, Jayson Tatum and others of note, Rozier is the lone untouchable when it comes time for the Celts to talk trade.

The sleek and slick guard laughs at that talk, though he noted it’s also been a theme in the room among his mates.

“That’s my guy, too,” Rozier told the Herald. “He’s good at what he does. He’s a businessman.

“And he played in this league, so he knows how players work more than a lot of these guys that have his job, because he’s been in our shoes before. That’s my guy.”

Particularly of late, Rozier has been making Ainge look bright, scoring in double figures in 18 straight games and averaging 15.8 points, 4.8 rebounds and 4.1 assists in 29.8 minutes over that span. He’s started in place of the injured Irving for five of those games, going for 19.4 points and 6.2 assists on those occasions.

But as well as Rozier’s doing, he acknowledged that he’ll be without an appendage of sorts for the next six or so weeks as his backcourt brother off the bench Marcus Smart rehabs from Friday’s surgery to repair a torn ligament in his right thumb.

Rozier has grown to truly enjoy and feed off the havoc they create.

“This is our third year together,” he said. “We played summer league together, too, and from that point on we just clicked.

“You know, you got just two crazy tough guys that’s out there. We just want to win, and we complement each other so well.”

Smart suffered the injury last Sunday night and is hoping to be able to play again this season if the Celtics can make it into the second round of the playoffs.

“It sucks that he had to go through that, especially after just being out with the hand injury and stuff like that,” said Rozier. “But it’s good that he’s not done for the rest of the year. He’s still got enough weeks to get it right.

“But, you know, he’s a tough guy. I know he wants to be out there with us to help us. He’s just got to take his time through the process and he’ll be fine.

“I’ve FaceTimed him and checked up on him. I told him we need him, but don’t ever rush nothing. You know, do what he feels is right. I just wanted to give him encouragement and let him know I’m there for him and stuff like that. I don’t ever want to bother anybody, but I’m going to reach out to him.”

Rozier may be reaching out to Smart again this summer when the latter becomes a restricted free agent. He’s more than willing to play a role in keeping the band together.

“Yeah, if I’m part of the plan in recruiting Marcus to stay here, then that’s what I’m going to have to do,” Rozier said.

“They know his value on this team. A lot of people in this league know his value and what he does for a team.”

And if one of those teams makes Smart a huge offer that brings into question whether the Celts will match, Rozier may have to call his pal Ainge.