LOS ANGELES — Kawhi Leonard’s presence is so massive, the public tone on the Los Angeles Clippers’ first-round series against the Dallas Mavericks shifts with every injury update on his right knee.

It’s almost as if the Clippers don’t have a wealth of players who, at a moment’s notice, can fill his shoes. It’s why their series-opening decisive 109-97 win felt like an upset, despite it taking place at Crypto.com Arena on Sunday afternoon.

Almost as if this was the semi-helpless bunch that couldn’t manage a second wind or a second win against the Phoenix Suns last year. Almost as if these Clippers don’t employ James Harden.

Both the Clippers and Mavericks seem to have a lot riding on this series and futures seem to be on the line. And each have had stretches where they could convince themselves of very long playoff runs.

That’s what makes this series so compelling. That’s why free-agents-to-be Harden and Paul George are so much in focus here.

Harden put on his Luka Dončić suit — or his own old suit — to set the tone from the beginning in a wire-to-wire win. He was hitting stepback 3s he made famous over the last decade, controlled the tempo and pace, and was even part of a defensive effort that held the Mavericks to eight second-quarter points as the Clippers amassed a 26-point halftime lead.

Twenty of Harden’s 28 points came in the first 24 minutes, and the Clippers had a game plan that stymied Dončić and Kyrie Irving. Dončić finished with a game-high 33 points and 13 rebounds while Irving had 31, but those halftime numbers were ghastly with Dončić scoring 11 and Irving managing just one field goal, a fast-break layup.

Ivica Zubac, who had been hunted by Doncic on switches in the last two playoff matchups, operated well in space defensively and punished Daniel Gafford on the other end. He had a double-double at halftime and finished with 20 points and 15 rebounds.

So much of that was Harden recognizing the mismatches, feeding Zubac and then when the moments presented, unleashing his own offensive game.

Harden isn’t the type to talk about his playoff struggles, but let a little air into the window of his psyche.

“I can score with the best of them — still,” Harden said. “My role for this team is generating good shots and making guys’ jobs easier. And when my number is called, score the basketball. Obviously Kawhi is out, so my volume is gonna go up.”

That “still” is doing a lot of work, an indication he knows there are doubts over whether he can rev it up and be more than a facilitator, while also being able to do it when it counts.

“It’s a huge element,” Clippers coach Tyronn Lue said. “He understands he doesn’t have to do a lot of heavy lifting when Kawhi and PG are on the floor. But when one of those guys are out, we need him to be an aggressive scorer. That’s what he’s been doing as of late.”

You give Tyronn Lue a week to prepare, you’re asking for trouble. When the Mavericks got things a little closer, he called a timeout and then unleashed George on a weak-side back cut that gave him a layup, two of his 15 second-half points, and allowed the Clippers some breathing room.

Make no mistake, after last year when the Clippers thought they had Phoenix on the ropes before Leonard’s injury, Lue lives for the chess match — even if he doesn’t have all the pieces at his disposal.

The Clippers were crisp, they played with force and physicality and focus — and his talk to Harden a week before about being more aggressive paid off. Harden’s struggles after the All-Star break were a cause for concern (38% shooting and 30% from 3 in 24 games), but for one game it seemed like he and the team were on the same page.

Being without Leonard was almost predictable. Not because he’d want to sit out a playoff game, but the signs were around: He hadn’t practiced in the days leading up to the series opener, he hadn’t played in an actual game since March 31, and even with that, he still qualified for season awards by crossing the 65-game threshold.

So it didn’t seem like a case of Leonard or the Clippers playing possum, or engaging in some subterfuge to throw off the Mavericks. The 4 vs. 5 seeding says the teams are evenly matched, but Lue and the Clippers are smart enough to know the Mavericks would be prepared for any contingency.

It was the Clippers who had to get their minds right, so they had more than enough time to know there would be no miraculous tunnel entrance for Leonard, the playoff destroyer. Call it bad luck or atrophy or anything else, but the Clippers have played their last four playoff games without him, as he missed the last three games of their first-round series against Phoenix last year.

But the final regular-season games gave Harden a chance to have that old thing back, to drive the car like he was used to when he was a one-man show. As much as he’s wanted things to revolve around him, as much as that was a source of frustration in Philadelphia, it’s still an adjustment to change your mindset and go out there with an aggressive tone.

He’s probably better served as a third option with first-option capabilities at this stage of his career. Depending on him to do it when a series winds down is asking a bit much, as his track record is undeniable.

His last playoff game before Sunday was forgettable, that Game 7 in Boston when nobody showed up for Philadelphia. But for two games he dropped 40-plus on the Celtics, and usually when a second-best player does that, it means a team has won a series.

Not the case there, but if Leonard comes back and is a reasonable version of himself, Harden has banked this game. Perhaps it means the Clippers can slow-walk Leonard’s return, because nobody knows if he’ll be ready for Game 2 in 48 hours.

Everything feels the same about Harden, everything feels the same about the Clippers, a match made in basketball snake eyes. But for once, they rolled sevens.