TAMPA, Fla. (AP) -- Doug Martin is back from an injury that sidelined him for most of last season and confident he can regain the form that made him one of the most productive running backs in the NFL as a rookie.
The third-year pro missed the final 10 games of 2013 after tearing the labrum in his left shoulder, contributing to the Bucs ranking 30th in scoring and last in total offense on the way to a 4-12 finish.
If the Bucs are going to turn themselves around in their first season under coach Lovie Smith, they likely will need a strong running game built around the 5-foot-9, 215-pound Martin.
Particularly with second-year running back Mike James slowed by a shoulder injury and third-round draft pick Charles Sims likely to miss a significant portion of his rookie season after undergoing surgery on his right ankle last week.
''He's a key guy,'' Smith said of Martin, adding that backup Bobby Rainey also figures prominently in the team's plans as it prepare for the Sept. 7 regular season opener against Carolina.
''With Mike James going down with an injury and with Charles going down, those guys need to play at a certain level,'' the coach added. ''They're both good players, but Doug is our bell cow. He likes that role. He's had a good camp, hasn't missed a beat.''
Martin rushed for 1,454 yards and 11 TDs in 2012, and his 1,926 yards from scrimmage ranked third in the NFL behind Adrian Peterson and Calvin Johnson. Only two players in league history - Eric Dickerson, with 2,212 in 1984, and Edgerrin James, 2,139 in 1999 - have gained more yards from scrimmage as a rookie.
''A tough runner, doesn't complain,'' Smith said. ''He's going to rush for a lot of yards for us this year.''
Tampa Bay's starters will get their most extensive playing time of the preseason Saturday at Buffalo. Like most of the regular, Martin expects to play into the third quarter.
So far this summer, he's gained 30 yards rushing on nine carries and caught two passes for 6 yards in two games. Despite limited production, Martin feels good about the progress of the new offense installed by first-year coordinator Jeff Tedford.
''I think we took another step - a step up - with the last game,'' the 25-year-old said. ''The line did a good job protecting the quarterback and creating lanes for us running backs. I felt like it was the key to the offense doing better than the first week.''
Despite playing behind an offensive line that struggled to create running space and protect the quarterback, Martin was on pace for another 1,000-yard season when he was injured during a loss at Atlanta on Oct. 20. He was inactive the next two games, then spent the final eight weeks on injured reserve, finishing with 456 yards and one TD rushing.
He's eager to play more against Buffalo this weekend to get a better gauge of where he stands.
''There's always room for improvement,'' Martin said. ''These live reps have definitely been useful to me. It's been since November that I've seen a lot of reps. So these preseason games have definitely helped me get back into the flow with game speed.''
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