NASHVILLE, Tenn. — The Tennessee Titans, off to a miserable 1-4 start, are starting to be hampered by serious injuries, too.

Within three days, the Titans found out that they are likely to be down two key starters, one on each side of the football, for the balance of the season.

First, safety Bernard Pollard tore his right Achilles tendon, and he underwent surgery Tuesday. Now, it appears as if the Titans will also be without stalwart left tackle Michael Roos for the remainder of the season. Roos was expected to have right knee surgery, which could end his Titans career.

Roos, in his 10th season, all with the Titans, is a free agent at the end of the season, and Tennessee already has his heir apparent in place: 2014 first-round draft pick Taylor Lewan from Michigan.

“Everything is going to weigh on it,” Roos said of having the surgery. “We’ll just have to see exactly what will happen. … It’s very likely.”

The loss of Roos is huge for the Titans, as he has missed only one game in his career. In 2012, he underwent an appendectomy but was back in the lineup after only one week out.

As for Lewan, the Titans have been toying with ways to get the him the field. Guard Andy Levitre has struggled, and there was talk of possibly using the rookie there. Lewan appeared in the past two games in some packages as an extra blocker, lining up at tight end.

Lewan insists he is ready for the challenge of stepping into the starting lineup, beginning this week against the Jacksonville Jaguars.

“That’s one of the reasons why I was drafted here, to eventually play left tackle,” Lewan said before word leaked out of the seriousness of Roos’ injury. “Whatever happens to Roos happens to Roos, but I’ve been preparing like I’m a starter every week. I’ve been learning from him since the day I got here, so that I’m prepared if I need to be.”

Meanwhile, quarterback Jake Locker missed practice Wednesday with an injured thumb. Two weeks ago, he missed practice during the week due to a wrist injury, and he sat out against the Indianapolis Colts, with Charlie Whitehurst making the start.

Locker is in a similar situation this week. He must wait for the swelling to go down in order to see whether he will be able to practice and play against Jacksonville.

“He wants to play, so we’ll monitor it day-by-day,” Titans coach Ken Whisenhunt said.