INDIANAPOLIS -- The Colts will be without starting left tackle Anthony Castonzo for Sunday's key game against the Jacksonville Jaguars and during the playoffs if they make it.
Castonzo will undergo season-ending right ankle surgery this week after there wasn't much progress with the ankle healing, coach Frank Reich said Wednesday. Castonzo missed the Colts' Week 16 loss at the Pittsburgh Steelers after injuring his ankle in practice Dec. 24.
"You feel sick for AC going down like he did on a Thursday practice," quarterback Philip Rivers said. "Maybe it was a matter of time before something happened. He's had a heck of a year, a big part of what we do offensively, run game and pass protection. He'll be missed."
Not that there is ever a good time to lose a quarterback's blindside protector, but the Colts need to beat the Jaguars and get help to make the playoffs for just the second time since 2014. To make matters worse, the player who started for Castonzo against the Steelers, Will Holden, has also been ruled out against the Jaguars due to an ankle injury.
Reich said they have an idea who will start at left tackle but aren't going to say anything yet because they still have several days of practice to iron things out.
"But we do have a Plan A and a Plan B," Reich said. "We'll work those out in practice this week. We have a way we are leaning toward going, want to practice it out and then kind of wrap it up and confirm it on Friday."
Castonzo is 23rd among 65 qualified tackles in pass block win rate and 22nd in run block win rate, according to ESPN metrics and NFL Next Gen Stats.
The good news for the Colts is that starting right tackle Braden Smith came off the reserve/COVID-19 list Wednesday. That means there is a possibility that Chaz Green, who started at right tackle against the Steelers, could slide to left tackle against the Jaguars.
There is significant risk in having Green start at left tackle, though. He played so poorly there earlier this season that the Colts slid All-Pro left guard Quenton Nelson to left tackle for several snaps when Castonzo left the game momentarily against the Las Vegas Raiders on Dec. 13.
Reich said there is a chance that Nelson, who had never played left tackle in the NFL before the Raiders game, could start there against the Jaguars.
"Our goal is to think what's our best lineup for this Sunday," Reich said. "Get the best five guys in there for this Sunday to win this game. That's how we're talking about it. Quenton is certainly an option."