BOSTON — In his first game since helping the Celtics win the NBA championship five months ago, Kristaps Porzingis picked up where he left off.

The 7-foot-3 center, making his season debut after undergoing offseason leg surgery, finished with 16 points, 6 rebounds, 2 assists, 1 steals and 2 blocked shots in 23 minutes for Boston, as the Celtics led by 29 points at halftime en route to a 126-94 victory over the LA Clippers at TD Garden on Monday night.

“I felt great,” Porzingis said with a smile. “It was a long rehab, and I was itching to get back out there with this team after winning a championship. It was a good beginning, good first game back.”

It was certainly that, as Boston jumped out to an early lead and never looked back, turning the final 24 minutes into an extended celebration of Porzingis’ return.

And, in his first game in five months, Porzingis immediately provided the combination of floor spacing and rim protection that amplifies Boston’s efforts at both ends.

In a sign of both Porzingis’ versatility and what life in today’s NBA is like, Porzingis — the tallest player on the court — took half of his shots from 3-point range, including from the top of the key on each of the first two possessions. After missing the first, he made the second one — the only one he’d make among six attempts.

Inside the arc, however, was a different story. Porzingis went 5-for-6 on 2-point shots — including a nice midpost bucket over James Harden and throwing down multiple lobs from teammates — though he joked he got “flat tires” on both of them due to a combination of his timing and his conditioning.

“It’s part of the process,” Porzingis said. “Especially the first game back. Little bit of timing on the jump, catching a flat tire here and there and stuff. It’s normal.”

But it was at the other end where Porzingis can potentially have an even bigger impact. Boston, which had the second-ranked defense last season, came into Monday at No. 10 this season with the 19th-ranked rim defense (after being first last season in that category).

On Monday, Porzingis was part of a Celtics defense that had a season-high 11 blocks — Boston hadn’t had more than nine in any game this season — and immediately became a deterrent, forcing Clippers besides Ivica Zubac (23 points and 10 rebounds) to go a combined 2-for-8 from the field.

“Yeah, 11 blocks tonight,” Celtics coach Joe Mazzulla said with a broad smile, when asked about how Porzingis can change things for Boston defensively. “It helps.”

Porzingis had been building toward Monday’s return for weeks. He said he was ahead of the rehab process at every step, and felt good as far back as a month ago. Although the timeline on his return to the court was originally slated for December or January, he practiced for the first time a week ago with the Maine Celtics, Boston’s G League team, and had been going through rigorous pregame workouts over the past week that indicated his return could come sooner.

When Porzingis was upgraded to probable around noon Monday in the wake of Boston’s 107-105 win over Minnesota on Sunday night, he then returned to the starting lineup for Boston for the first time since sustaining a calf strain in Game 4 of Boston’s first-round playoff series against the Miami Heat.

To begin this season, Boston hasn’t missed a beat without Porzingis, as the Celtics are on pace to exceed last season’s 64-18 regular-season record and are averaging 50 3-pointers attempted — which would shatter the previous NBA record.

But that didn’t dampen the enthusiasm for his return. Porzingis received a massive ovation during pregame warmups from fans surrounding the court, and then another when he was announced as a starter.

The 48 minutes of game action that followed then became a continuing celebration of his return, and the potential this group has to become the first Celtics team to repeat as NBA champions since 1969 — with Porzingis, and his two-way versatility, being a key component.

“It’s going to change night to night, and we’re a versatile team,” Jaylen Brown, one of six Celtics in double figures with 16 points, said of Boston’s many ways of playing at both ends. “We have a lot of luxuries where different guys can do different things. The key is just to stay motivated and have a great mentality.”