INDIANAPOLIS – The Indianapolis Colts could be without Anthony Richardson for at least a month.

It’s possible the team will place its rookie starting quarterback on the injured reserve list after he sustained a sprained AC joint in his right shoulder in Sunday’s win over the Tennessee Titans.

NFL Network reported Richardson suffered a grade 3 sprain while ESPN, citing a source, reported Richardson is seeking a second opinion on his shoulder from shoulder specialist Dr. Keith Meister.

While the team hasn’t provided an official update on his status as of Monday morning, Richardson almost certainly will miss Sunday’s road trip to Jacksonville.

Being placed on IR would mean Richardson must miss at least four games before returning. The earliest he could return is the Nov. 11 game against New England in Germany.

The Colts have their bye week after the Patriots game, so it’s possible they would hold him out until the Nov. 26 game against Tampa Bay at Lucas Oil Stadium.

Sunday marked the third time Richardson has failed to finish a game he’s started because of injury. He missed the Week 3 game at Baltimore with a concussion.

Richardson suffered a bruised left knee and sore ankle in the opening loss to Jacksonville, then sustained a concussion in the first quarter at Houston.

Against the Titans, the No. 4 overall pick in the draft sprained his AC joint on a designed quarterback run in the second quarter. At the end of the 4-yard run, Richardson was taken down by linebacker Harold Landry, and the 252-pound linebacker fell on Richardson.

Shane Steichen has addressed the balance the team faces in maximizing Richardson’s threat as a runner with the injury factor. He noted Richardson ran a similar play against the Rams and “he popped a big one.

“Then obviously this week he got the shoulder on that play. That’s stuff that you’ve got to look at, be smart with, and it’s part of the game and you don’t want it to happen for sure.’’

Steichen also is aware the toll the injuries can have on a rookie.

“You’ve got to fight through those things, and that’s part of the league,’’ he said. “You’ve got to have the conversations that will build you stronger.

“Sometimes in life with any type of deal, you get nicked up, like ‘Why does this happen to me?’ You’ve got to think about the positive and think that obviously something good is going to come out of it in the end.’’

While Richardson heals, Gardner Minshew II will step in.

After five games and while seeing extensive action, Minshew has completed 57-of-83 passes (68.7%) for 553 yards and two touchdowns.

The Colts are off to a 3-2 start and tied with Jacksonville for the AFC South lead.