After initially holding out hope that their middle linebacker would be able to play again this season, the Seahawks have decided to place Lofa Tatupu on season-ending injured reserve.

Tatupu tore his left pectoral muscle during the first half of a Week Six game against Arizona while trying to make a tackle.

Because the muscle and tendons weren't completely detached from the bone, the Seahawks held out hope that Tatupu could return this season. However, Tatupu met with renowned surgeon Dr. James Andrews on Wednesday, and the decision was then made for Tatupu to undergo surgery Thursday afternoon to reattach the muscle.

Second-year LB David Hawthorne will replace Tatupu in the starting lineup Sunday at Dallas. In his only previous start, in Week Three when Tatupu was sidelined with a strained hamstring, Hawthorne made 16 tackles and intercepted a pass against Chicago.