INDIANAPOLIS – Concerns have lingered on the Indianapolis Colts’ banged-up defense in the wake of Sunday’s 37-34 loss against the Jacksonville Jaguars.

Now the offense also is muscling into the conversation.

ESPN’s Adam Schefter reported – and several media outlets confirmed – wide receiver Michael Pittman Jr. is dealing with a back injury, and injured reserve is not being ruled out as an option.

The Colts (2-3) played without three offensive starters – quarterback Anthony Richardson (oblique), running back Jonathan Taylor (ankle) and center Ryan Kelly (neck) – against Jacksonville, and wide receiver Josh Downs (toe), running back Trey Sermon (collarbone) and right tackle Braden Smith (knee/ankle) joined Pittman and Taylor as non-participants in Wednesday’s practice.

Adding to the degree of difficulty, Indianapolis is preparing to face a Tennessee Titans defense that has surrendered the fewest total yards (975) and first downs (56) in the NFL this season.

Speaking before the news of Pittman’s injury severity broke, Colts head coach Shane Steichen said he was encouraged by the offensive success without several starters last week.

“Our motto this year is determination never rests,” Steichen said. “We can’t rest in anything we do. We have to keep going and keep going and keep improving. Whether you win or lose, there’s always stuff to clean up, right? It’s constructive criticism. It’s accountability, and that’s what we’re all about.”

There is some optimism Richardson could return this week.

The 22-year-old looked stronger throwing during the early portion of practice open to media, and he said he’s feeling much better than a week before. But he was still listed as a limited participant.

Among the keys Richardson, the coaches and the medical staff will be looking for this week is the quarterback’s ability to play the game with his normal skill set.

Or as close to it as possible.

“I can run. I can throw. I can do the stuff that they want me to do in the offense,” Richardson said. “So, we’re just going to take it day-by-day and see how the rest of the week is.”

Joe Flacco completed 33 of 44 passes for 359 yards with three touchdowns and no interceptions in place of Richardson at Jacksonville.

Flacco has thrown for at least 300 yards in five straight starts dating back to last season with the Cleveland Browns, and he’s thrown at least two touchdown passes in seven straight appearances.

Indianapolis put up a season-high 447 total yards against the Jaguars but rushed for a season-low 99 yards.

The Colts scored on four straight possessions prior to their final drive with 17 seconds left, but the offense produced points on just two of its first seven possessions – including a 12-play, 71-yard scoring march to open the game.

“You always go back to the film, and there’s probably five to 10 things that you could look at and kind of question whether they might make a difference or not,” Flacco said. “I think even when you win the game – that’s the trouble when you look at the film. Even when you win games, there are plays like that where if you didn’t win, you’d be questioning if they were the difference-makers.

“You just have to be ready to go at all times, and I think we did a good job fighting through everything and being ready and giving ourselves the best chance.”

Indianapolis will try to get its first win against a division opponent Sunday at Tennessee (1-3).

But Richardson said there’s no added urgency this week.

He’s missed 14 of 22 career games due to injury, and his goal is to be available for his teammates every week.

“Of course, dealing with injuries, nobody wants to be on the sideline, but I’m just working with the trainers day-by-day,” Richardson said. “I’m in here in the morning making sure I’m getting my body right, and I’m also in the film room and the meeting room making sure I am prepared if I am playing. So, I think it’s very important to try to get back.”

INJURY REPORT

There was some good news Wednesday.

Cornerback Kenny Moore II (hip/shoulder) and defensive end Kwity Paye (quadricep) – who missed each of the past two games – joined Richardson as limited practice participants.

Kelly practiced in full.

Safety Jamal Adams (hip), wide receiver Treylon Burks (personal matter) and defensive tackle Keondre Coburn (knee) did not practice for the Titans.

Wide receiver DeAndre Hopkins (rest), defensive tackle Jeffery Simmons (elbow) and cornerback L’Jarius Sneed (rest) were limited.

Linebacker Cedric Gray (shoulder), linebacker Ernest Jones (elbow) and quarterback Will Levis (right shoulder) were full participants.