The Heat is getting used to winning without Dwyane Wade.

Miami is 4-0 this season in games without Wade, who missed Tuesday’s 120-98 victory against the San Antonio Spurs with a sprained ankle. The Heat, which snapped a three-game losing streak, struggled through the first half at AmericanAirlines Arena but then came to life in the third and fourth quarters behind dazzling shooting efforts from LeBron James and Mike Miller.

James, who played despite flu-like symptoms, led the Heat with 33 points on 12-of-21 shooting. He shot 1 of 6 to begin the game but caught fire in the second and third quarters. James was 11 of 15 from the field and 4 of 5 from three-point range the second half.

Mike Miller, returning to action for the first time this season, had 18 points and was perfect from the field, shooting 6 of 6 from three-point and four rebounds. Heat coach Erik Spoelstra said he only planned to play Miller five or six minutes but Miller played more than 15.

“He said he was ready to go 10 days ago, and we held him out these extra days,” Spoelstra said.

The Heat trailed 63-49 after the second quarter — the Spurs shot 66.7 percent in the first half — but it didn’t take Miami long to erase the deficit. James made his first three-pointer with 5:23 left in the third quarter to give the Heat a 69-68 lead. It was the Heat’s first lead of the game, and Miami never surrendered it.

“We weren’t playing by our standards, defending,” James said of the first half. “They shot 60-plus percent, and we can’t allow no team, especially on our home floor, to do that.”

The Heat made amends, outscoring the Spurs 39-12 in the third quarter. The 27-point differential marked the second largest scoring margin for a quarter in franchise history.

Torrid run

At one point in the first half, the Heat trailed by 17 points but a 29-3 run in the third quarter wiped that away and also wiped away any chance of the Spurs’ first road victory of the season.

While the Heat shot 75 percent from the field in the third quarter (15 of 20) and 75 percent from three-point range (6 of 8), the Spurs were 4 of 19 from the field for 21.1 percent and 1 of 7 from three-point range for 14.3 percent.

“Clearly a tale of two halves,” Spoelstra said. “It wouldn’t have changed if we didn’t make a change defensively.”

James’ four three-pointers were one more than his season total. He also had 10 assists and five rebounds. Not to be outdone, Chris Bosh had 30 points on 14-of-22 shooting and carried the Heat during the first half, when James’ illness appeared to be sucking the life out of him.

Bosh’s highlight of the game — perhaps the highlight of his season thus far — came in the fourth quarter when he did a spin move around defender Tiago Splitter in the middle of the lane before slamming down a powerful one-handed dunk. The impressive display of athleticism gave the Heat a 97-82 lead.

While James began the game sluggishly — later saying he couldn’t catch his breath until the second quarter — he found his reserve tank of energy quickly in the third quarter.

He had 17 points in the period and, along with Mario Chalmers, put on a shooting clinic. James and Chalmers combined to make four consecutive three-pointers.

Chalmers, who finished with 13 points, made his second three-pointer of the quarter with 1:30 to play and gave the Heat an 83-70 advantage. Chalmers finished 4 of 6 from three-point range.

Spoelstra credited the scoring burst to the Heat’s defense.

Miller time

“Make no mistake about it,” Spoelstra said. “The commitment to activity in the second half was about as good as we can be.”

Shortly after Chalmers and James cooled down, Miller took over. He made his first three-pointer with 30.9 seconds left in the third quarter and then had five in the final period.

His final bucket of the night gave the Heat a 110-87 lead, and Miller received a standing ovation from the crowd when he checked out of the game.

“They’re all good looks,” Miller said. “Obviously, I didn’t shoot as well as I wanted to last year. Is that because I had broken thumbs? I don’t know. I’m not using that as an excuse, but I feel like I can makes shots.

“I felt good tonight and, obviously, they went in.”