Tom Thibodeau didn’t want to mess with his effective second unit when Mitchell Robinson went out of the lineup last week, but another injury forced backup big man Isaiah Hartenstein into the starting lineup for the first time this season Wednesday night against the Nets.

With Jericho Sims expected to be reevaluated in 7-to-10 days with a sprained right ankle, Hartenstein started at center ahead of recently re-signed veteran Taj Gibson.

Sims had started the previous five games before turning his ankle in the first quarter of Monday’s road victory over the Lakers.

He averaged 15.4 minutes in the five games, with Hartenstein logging 31.2 per appearance off the bench, including a season-high 39 against the Lakers after Sims departed.

The 38-year-old Gibson played last season with the Wizards after spending the previous three years with the Knicks. He also has played for Thibodeau-coached teams with the Bulls and the Timberwolves.

Gibson joined the Knicks on their recent western road trip, totaling 13 minutes over the final three games against the Suns, Clippers and Lakers.

“He’s always ready, just get in there and get the job done,” Knicks coach Tom Thibodeau said before the game. “One of the things that we like about him is he’s played every role. He’s played power forward, he’s played center. He’s been a starter, he’s been a sub. He’s been out of the rotation and adds value in whatever role you ask him to play.

“He’s the ultimate teammate.. Just get in there and get the job done.”

Thibodeau also said that he considered employing smaller lineups involving power forward Julius Randle or even 6-foot-4 wing Josh Hart at center, depending on matchups.

“He could. You could completely downsize,” Thibodeau said. “He has the ability to guard every position. Particularly, it depends who they have on the floor, too. So that factors into it.”

Hart has been serving as Randle’s backup at power forward this season after Obi Toppin was traded in the offseason.