DENVER — The Denver Nuggets were cruising toward a key win over a Western Conference opponent Tuesday. With 4:24 remaining in the third quarter, they took a 19-point lead over the Los Angeles Clippers. Paul Millsap’s first game back since he injured his wrist Nov. 19 was going swimmingly.

Then Denver hit a 7-foot-3 iceberg.

Boban Marjanovic, who the Clippers acquired in late January as a part of the Blake Griffin deal, was inserted into the lineup at the 4:06 mark in the third quarter. From that point on, the Clippers outscored the Nuggets by 21 points as Denver fell 122-120.

“It happened so fast, I don’t even know what to say,” Will Barton said. “Big fella on their team, he changed the game for them. Just a bad loss.”

Marjanovic had logged a grand total of one minute for the Clippers before he checked into Tuesday’s game. When he finally got in, Denver had no answer for his size. He scored 18 points in 15 minutes. He made 5-8 shots and sunk 8-9 free throws. Los Angeles outscored Denver by 27 points with him on the floor.

Marjanovic and the rest of the Clippers’ reserves bludgeoned Denver. Lou Williams poured in a game-high 25 points. Montrezl Harrell had 15. Milos Teodosic chipped in with 11.

“Obviously, that 13-2 run snowballed into a 30-6 run with Boban being a very big part of that,” Nuggets coach Michael Malone said. “His size and his length. He got five offensive rebounds, and we gave up 70-plus points in our paint. That’s a tough loss. … We stopped playing the way that got us in the lead by defending, by sharing the ball and by attacking.”

Marjanovic crushed Denver in pick-and-roll situations. All five of his makes came at the rim. His dunk with 3:17 remaining pushed the Clippers’ lead to seven.

The Nuggets kept it close, but with his team down two and time running out, Jamal Murray turned it over on a drive down the floor. It was Denver’s 20th giveaway of the game.

“Just watching that play, and I’ll watch it with Jamal, he’s got to realize that as he comes off that and there’s still two on the ball, Nikola Jokic is open. That ball’s gotta get to Nikola in that situation. Now do I love the fact there’s a recently turned 21-year-old point guard looking to be aggressive? Sure. Like we talked about earlier in this season, it’s not about making the play in those situations. It’s about making the right play. If you draw two defenders, and you have Nikola Jokic wide open, I would have preferred to have that pass made.”

The Clippers hung 41 points on the Nuggets in the fourth quarter. The loss dropped Denver to ninth in the crowded Western Conference — one spot out of the playoff picture. In the end, there was too little defense, too many turnovers and way too much Boban.

“Like I said, the big fella for them really changed the game,” Barton said. “I thought we were playing pretty good defense throughout the game, especially the first half, and then they put him in the third quarter and that second group came in. It’s tough.”