The Rams and Colts will square off for the first time since 2013 to begin the regular season, and Indianapolis will arrive at the Coliseum a bit shorthanded.

Top cornerback Vontae Davis has been ruled out with a groin injury. Center Ryan Kelly suffered a foot injury and has also been ruled out.

But quarterback Andrew Luck's shoulder injury has garnered the majority of the headlines — and with good reason. Luck played through a shoulder injury in 2016, en route to completing 64.5 percent of his passes for 4,240 yards with 31 touchdowns and 13 interceptions. He was sacked a league-high 41 times, and underwent offseason shoulder surgery to repair the damage.

Luck began training camp on the Colts' physically unable to perform list and stayed there until rosters were reduced to 53 players. Indianapolis general manager Chris Ballard told reporters earlier this week that there's still no timetable for getting Luck back on the field, which Colts head coach Chuck Pagano reiterated on a Wednesday conference call with Los Angeles media.

"He's doing well. He's in a good place," Pagano said. "When the doctors and trainers let us know that he's able to get back into practice and those kind of things, then start to integrate him back in."

Enter Scott Tolzien, who served as Luck's backup last season. He'll start this week against L.A. as Luck continues to recover.

"I've got a lot of respect for Andrew Luck. To say that I'm disappointed not to see him… I probably wouldn't say that," Rams head coach Sean McVay said with a laugh on Wednesday. "But, what I would say is that [I have] a lot of respect for them as a team, for Scott Tolzien. And we know that it's going to be a great challenge."

Indianapolis also acquired quarterback Jacoby Brissett from New England late last week in exchange for wide receiver Phillip Dorsett. He'll enter Sunday's game as the No. 2 signal-caller.

"We got a phone call there at cut down time and things like that and we had a chance to acquire a really good young talent in Jacoby, so we're excited to have him in the mix," Pagano said. "Coaches are obviously busy with him being the No. 2 and the backup, getting him up to speed and getting him as prepared as we possibly can in case he's got to go in there for whatever reason."

As significant as Luck's absence is, Kelly's injury could also play an important role in determining Sunday's outcome. Undrafted rookie Deyshawn Bond will make his debut starting at center this week. Bond is an Indianapolis native, and the Colts signed him out of Cincinnati after seeing him at their local pro day.

"We're really grateful, thankful that we got '007,' as they call him in the room," Pagano said, referencing Bond's last name. "He had a great offseason, great OTAs, camp – thrust into the starting role and he's done a great job and he's been a really consistent performer for us at that spot. … This will be a different level, we all know that, but he will go out and trust his preparation and trust his fundamentals and his technique and the guys that play around him."

The Colts' offensive line has generally been in flux, with players like Jeremy Vujnovich going from right tackle to left guard on this week's unofficial depth chart. Nevertheless, Pagano told reporters this week he's "never felt better about an offensive line or a football team."

"Never felt better. You guys can write it, put it on record, hold it to me," Pagano said, via ESPN. "We'll come in [following the game] and there's going to be some mistakes made. But we're going to dress seven, maybe eight guys. All those guys will be prepared to play good football."

What will likely help is having running back Frank Gore leading the ground attack. While Gore's in his mid-30s, he's still putting up consistent, solid numbers for a running back. He's No. 8 in all-time rushing yards with 13,065 — including 1,025 last year — and hasn't shown many signs of slowing down.

"I don't know Frank personally, but I've been around a lot of people that have been around Frank and it sounds like he's all about the right things," McVay said. "He's one of the more patient runners. I think he's got a great feel for when he squares his shoulders off downhill. He's able to just feel the way that a defense pursues and he always seems to get the ball in the right place based on the way that the plays blocked. Works edges on people, great ball security. He's a guy that, he had a bunch of carries last year — only lost one fumble.

"So I think when you look at over the course of his career, when you see 13,000 yards, that production speaks for itself," McVay added. "Just watching the way that he competes he seems like he's all about the right kind of stuff and you respect that as a coach."