PITTSBURGH — The Pittsburgh Steelers will be without key starters on their offensive and defensive lines when they face the Jacksonville Jaguars on Sunday.

Right tackle Marcus Gilbert will miss his fourth straight game with a knee injury, while defensive end Stephon Tuitt has been ruled out with an elbow injury. Second-year player Matt Feiler will fill in for Gilbert as he has the past three weeks, while nine-year veteran Tyson Alualu is set to replace Tuitt.

“I think you just always have to be ready and be prepared when you do get opportunities to play more,” Alualu said. “You just have to make sure there’s no drop-off when someone goes out, especially with it being Tuitt because we all know what he’s capable of and what he’s done.”

Gilbert has only played 13 of the team’s last 25 games after missing just three games the previous two seasons.

It will be Feiler’s fifth start of the season and sixth of his career. He has already started four games this season. The first came in Week 3 against Tampa Bay, the Steelers’ first win of the season, when Gilbert sat with a hamstring injury.

“I’m just trying to stay ready because you never know when they’re going to need me,” Feiler said. “I’ve just been preparing like I have been every week like I’m going to be playing.”

The Steelers have won all four times Feiler has started at right tackle, including the last three games. Those wins were part of a five-game winning streak that has helped the Steelers climb atop the AFC North after a 1-2-1 start.

The Steelers have averaged 424 yards of total offense the previous three weeks, including 140 on the ground. James Conner, third in the league with 771 rushing yards and 10 touchdowns, has rushed for more than 100 yards in two of the last three weeks. Conner will play Sunday after leaving last week’s win against Carolina with a concussion.

“Every lineman wants to run-block and kind of push other guys around,” Feiler said. “We’ve been clicking. We’ve been staying on the field longer and keeping our momentum. It’s a lot of fun.”

Alualu will get the start against Jacksonville, a city where he spent his first seven seasons before signing with the Steelers.