RENTON -- Left guard Robert Gallery suffered a groin injury in the first quarter of Sunday's game at Pittsburgh, and while he finished the game, he will need to undergo surgery and will be out the next four to six weeks.

Paul McQuistan is the next player up to replace Gallery at left guard. Rookie James Carpenter -- who started in Gallery's place at left guard in Week 1 -- will remain on right tackle.

Gallery, 31, was signed this offseason to be the one veteran starter on Seattle's offensive line. He suffered a sprained knee in the Seahawks' final exhibition game, which kept him out for the season-opener, and now is down with a groin injury.

"It has been something that has been bothering him," coach Pete Carroll said of Gallery's groin injury. "He has had a groin issue that we thought, after the couple of weeks with his knee, that would get better. But it actually went the other way because of favoring the other side. He got a little more vulnerable, and he studded it out and played through it. He shouldn't have, but he did, and made it through it. We didn't know about it until after the game."

Gallery is in his eighth season in the NFL, and he was the one veteran on the offensive line that included three first-time starters in Week 1.

"He's an important guy to us," Carroll said. "We've loved having him. He's a fantastic character on your team, personality and all. The experience he has been through, the knowledge that he has helps other guys so you miss that. There's no replacing that. It was good to have him out this week working with us, but it is what it is. Paul (McQuistan) and Breno (Giacomini) and those guys have to step up and be ready to play for us."

Wide receiver Sidney Rice -- one of Seattle's other signature free-agent acquisitions -- is expected to practice this week, but a decision on his availability for Sunday's home opener against Arizona won't be made until after this week of practice, Carroll said.