INDIANAPOLIS — Back-to-backs have troubled the Nets all season.

They had better start clearing that hurdle quickly.

The Nets, who lost 121-100 to the Pacers on Saturday night, are 4-7 on the second night of back-to-backs.

They play Sunday night in Austin, Texas, against the San Antonio Spurs needing to make some headway in that department.

They began the season a dismal 2-7 on the tail end of back-to-backs before winning their last two: a 112-107 victory against Philadelphia on March 5, and rolling to a 120-101 laugher in Cleveland five days later.

But Mikal Bridges has struggled on short rest and is already in a funk.

He finished with seven points on 1 of 8 shooting in Saturday’s loss.

Coming into the weekend, Bridges was averaging just 16.7 points on subpar .392/.333/.727 shooting splits in his last 13 games.

There are the quirks of the NBA schedule, and then there is this.

The Nets went the first 66 games of the slate without playing Indiana a single time, but now are facing the Pacers three times in the last 16 games, including Saturday night at Gainbridge Fieldhouse.

“Yeah it’s a little different. You haven’t seen them, and they play a unique style,” interim head coach Kevin Ollie said. “They are up and down the court, play with a bunch of pace. It’s not a lot of patterns to it; it’s a lot of rhythm. And they have some great guards and they play with pace and we have to get back.”

The Nets were 13 of 18 from the foul line in the first half Saturday, the second-most free throws they’d taken in a first half this season. They were 15 of 20 in the first half Dec. 2 against Orlando.

Bridges’ first 3-pointer against Indiana was his 170th of the campaign, moving him into seventh place in Nets single-season history. Next up is Joe Harris in sixth with 172 in 2019-20.

Ben Simmons is out for the season after undergoing a microscopic partial discectomy on Thursday.

First-round pick Dariq Whitehead is traveling with the Nets but is also out for the season after having surgery for a shin stress reaction in January.

Fellow first-round pick Noah Clowney got called up from Long Island on Saturday morning. He averaged 25.5 points and 9.5 boards in his prior two games in the G-League.

He was scoreless in four minutes of action in Saturday’s loss.

Doug McDermott (right calf strain) and Bennedict Mathurin (labral tear in his right shoulder) were out for Indiana.