Jericho Sims is going from out of the rotation into the starting lineup.

The third-year center started in place of the injured Mitchell Robinson Monday night against the Raptors at the Garden.

It isn’t a complete surprise that coach Tom Thibodeau went with Sims over backup Isaiah Hartenstein. Last year when Robinson was out, Thibodeau also started Sims to keep the second unit intact.

The 6-foot-10 center started 16 games last season.

This year, Sims has only appeared in nine games and has yet to log more than seven minutes in a single appearance. That will change now obviously.

“He’s done it before. Every opportunity he has gotten he has already been ready for that opportunity,” Thibodeau said. “Injuries are a part of the game, and that’s why you have a roster of 15. When one guy goes out, the next guy [has to] be ready to step in and get the job done. And that’s what I like about [Jericho].”

The 7-foot Robinson suffered a stress fracture to his left ankle in Friday’s loss to the Celtics and will undergo surgery this week.

The team said he will be reevaluated in 8-to-10 weeks, meaning Robinson will likely be out until March.

At least initially, the Knicks’ depth in the middle will be tested in that time span.

“We’re not going to change [our] style of play. A lot of the things Mitch does Jericho does as well,” Thibodeau said. “With Isaiah, it’s different. I like having that flexibility. It’s two different looks, a center who can play away from the basket and open things up.”