LOS ANGELES >> The usual routine was disrupted by an unexpected but welcome notification on Braxton Key’s phone.

It was Tuesday, before a preseason game against the Clippers. “I came back from my shootaround and I took out my phone,” Key said. “Usually I text my girl and a couple other people.”

But this time he was surprised to see a text from Michael Malone, who was still on personal leave following the death of his father a week earlier.

He was imploring Key to slow down on offense. Malone liked how Key was defending and using his physicality, but he thought Key looked a bit uncomfortable at the other end, a natural growing pain for a player adapting to a new system.

“I was just doing some things that were uncharacteristic,” Key said. “Trying to do a little too much at the offensive end. So I listened to him.”

Key played his best game of the preseason that night, scoring 14 points and grabbing 10 rebounds.

Malone, the ninth-year Nuggets coach who led the franchise to its first NBA championship in June, texted as many young role players as could before Tuesday’s game, trying to offer bits of advice for each of them.

He officially rejoined the team in Los Angeles the next day, but in the meantime, Malone did his best to keep on coaching in a time of grief. Even if it was just a contribution as small as those texts.

“Knowing that my father was a big part of this,” Malone said, “I take that to heart and hope I can continue to make him proud.”

Brendan Malone was in the NBA for 30 years, most famously instituting the “Jordan Rules” defensive strategy used by the Pistons against Michael Jordan. In Detroit, he won two championship rings. He lived to see Michael win his first, but died at 82 just days before Denver’s title defense began. Calvin Booth and the Nuggets front office came to the funeral, as did former general manager Tim Connelly.

Now Michael will accept his ring Tuesday night.

He always envisioned the version of a championship ring that they handed out in his dad’s era, “like a regular-ass school ring.” Not the diamond-encrusted, customized accessories awarded in the modern NBA.

“These things open up and they shoot beams out of them,” he said. “I don’t know. … I think more for me, it’s how symbolic it is, that you get a ring for being a champion. I think it’s pretty cool. My dad just passed away, but I believe that my father and I are the only father-son duo in NBA history to both have world championship rings. So that kind of makes it even that much more meaningful to me and my family.”

Malone emphasized throughout training camp that a season opener is a terrible time to live months in the past.

He has said he can’t wait for the ceremony to be over. He still sort of thinks that, but he also feels more inclined now to appreciate the moment and cherish what he got to share with the coach who inspired him most.

So in that vein, Malone got back to coaching even before he got back to his team. After all, players were competing for minutes, trying to make the most of the preseason reps.

Getting after it on the glass was paramount for second-year wing Peyton Watson. “He just told me to continue to rebound the ball, play hard on defense, create my niche, and also that for me with the talent that I have, less is more,” Watson told The Post. “Continue to do simple things and it’ll all pay off. … Tried to do my best to carry out what he wanted me to do.”

Julian Strawther’s text was a role model recommendation. Malone wanted the sharpshooting rookie to find inspiration in Klay Thompson.

“What I’ve always admired about Klay Thompson is that Klay has been elite on both ends of the floor,” the coach said. “And that’s what I want Julian to be. I don’t want him to be an elite shooter; I want him to be an elite basketball player who impacts the game on both ends.”

Rookie Hunter Tyson, who excelled in the Summer League, was going through a preseason shooting slump. He was 5-for-19 from beyond the arc. Brendan Malone spoke through Michael’s text to the Clemson grad.

“I said don’t ever lose your confidence,” Malone recalled. “That’s something my father told me for years. Don’t let anybody take away your confidence. I said, ‘Hunter, you’re a good shooter. And I see you hesitating now, I see you tentative.’ I said, ‘If you’re open, shoot the ball. Make or miss, shoot the ball. That’s what you do.’”

Tyson scored 19 that night on 6-of-12 shooting, with three 3-pointers.

When Malone was back the next day, the constructive criticism expanded. He got on the Nuggets for poor rebounding and transition defense in a film session.

He was still catching up himself, having not watched much of the first three preseason games. Last week was hard. Now he could get back to coaching, like his father before him.