“He’s done a good job,” Shanahan said of Hightower on Saturday. “I’m not going to say he’s our starter, but if you were betting in Vegas, you’d probably go in that direction.”

Hightower has carried 25 times for 170 yards and two touchdowns since being acquired in a trade with the Arizona Cardinals at the start of training camp. Torain sustained his hand injury in practice earlier this month, but Shanahan said Saturday that the team’s leading rusher in 2010 would appear in Thursday’s preseason finale against Tampa Bay. Torain practiced on Saturday.

“You’re looking for competition, but Tim has done a fine job, both in the running game and the passing game,” Shanahan said. “Now Ryan gets a chance to come back and show us what he can do.”

Torain began last season on the practice squad, but he finished with 742 yards on 164 carries — a 4.5-yard average — with four touchdowns in 10 games, eight of which he started. He is, however, notoriously prone to injury. He missed time a year ago with a hamstring injury, and missed all of the 2009 season after a knee injury. An elbow injury caused him to miss nearly half of his rookie season with the Denver Broncos.

Shanahan said rookie Evan Royster will also play against the Buccaneers, a week after fellow rookie Roy Helu received a team-high 14 carries against Baltimore. Shanahan said he hadn’t yet decided how long to play veterans and projected starters against Tampa.

“It’s a combination of everything,” Shanahan said. “A lot depends on injury. A lot depends on how we practice. A lot goes into it.”