Robert Gallery will have surgery to repair a groin injury and be sidelined four to six weeks, coach Pete Carroll just announced during his day-after news conference.

Gallery was signed in free agency to add some experience to the Seahawks’ young line at left guard, but he aggravated an existing situation in the first quarter of Sunday’s 24-0 loss to the Steelers in Pittsburgh.

With Gallery out, Paul McQuistan is the likely replacement at left guard as the team begins preparing on Wednesday for Sunday’s home opener against the Cardinals at CenturyLink Field.