Thomas has missed both of the Saints' playoff games because of an unspecified chest injury that he suffered in Week 17.
Thomas has been a valuable part of the Saints' offense all season as a runner, a receiver and a pass protector.
But the Saints do have depth at the running back position –- which they proved last weekend when Mark Ingram, Darren Sproles and Khiry Robinson combined to help New Orleans run for 185 yards in a 26-24 victory over the Philadelphia Eagles.
That run game will be key for the Saints in what's expected to be wet and windy weather -- not to mention Seattle's No. 1-ranked pass defense.
Lewis was expected to play after practicing fully all week. He left last Saturday's wild-card game early with a concussion. Hicks was limited in practice all week with an ankle injury. He's an underrated starter on the interior of New Orleans' line, especially as a run defender.