A league source had told ESPN NFL Insider Adam Schefter on Monday that Locker wasnt' expected to play against the Vikings due to a separated shoulder.
Locker injured his left shoulder after being sacked in the first quarter against the Houston Texans in last Sunday's 38-14 loss.
Hasselebeck, who replaced Locker against the Texans, completed 17 of 25 passes for 193 yards and two touchdowns. He also threw two interceptions that were both returned for Houston touchdowns.
Munchak also announced Rusty Smith will back up Hasselbeck against the Vikings.