SANTA CLARA, Calif. (AP) -- Training camp is not even a week old and already the San Francisco 49ers' depth at running back is about to be tested.
The 49ers said Saturday that reliable backup Kendall Hunter tore the anterior cruciate ligament in his right knee during Friday's practice, ending his season before it began. Hunter started training camp where he has been most of the last three years: as the No. 2 running back behind Frank Gore.
''You just got to try to play for him,'' said James, who has wanted more of a role in the offense. ''That's the way I got to look at it, is to try and go out there and compete. When I feel like I just can't give it anymore, I got to give a little extra for him.''
The extent of Hunter's injury came as a surprise to teammates.
Hunter's knee buckled awkwardly as he tried to make a move during a non-contact drill. He was able to walk off the field on his own before an MRI confirmed the tear.
Hunter had spelled Gore more than anybody the past three years. He burst onto the scene as a rookie in 2011 and started strong in 2012 before missing the final two months of the season - when the 49ers advanced to the Super Bowl, losing to the Baltimore Ravens - with a torn left Achilles tendon.
Hunter, who was entering the final year of his contract, rushed for 358 yards and three touchdowns on 78 carries last season. He has averaged 4.6 yards per carry since San Francisco selected him in the fourth round of the 2011 draft out of Oklahoma State.
''Only word that can describe it is devastating,'' said cornerback Chris Culliver, who was rooming with Hunter during training camp after spending the past year rehabbing from his own ACL tear. ''It's so easy to do that, but it's so hard to come back from.''
Now it's likely up to James, Hyde and Lattimore to ease the burden on the 31-year-old Gore in a running game that has been among the NFL's best in recent seasons.
James, the former Oregon speedster, is the most likely candidate - though 49ers coaches would still like to see him improve in pass protection. And while he fell out of favor last season as he mostly just returned kicks and punts, James has shown the ability to be effective in the read-option game with quarterback Colin Kaepernick.
James averaged 4.6 yards per carry in four regular-season games and 5.9 yards in two playoff games and the Super Bowl after Hunter injured his Achilles in 2012. He said he has worked on getting stronger to bounce off hard hits, starting his career at 190 pounds, playing at 200 pounds last year and bulking up to 208 pounds this offseason without losing any of his quick-cutting ability.
''I'm still fast,'' James said.
Hyde has all the physical tools that 49ers coach Jim Harbaugh and offensive coordinator Greg Roman crave for their power running game. Whether he is ready to contribute as a rookie is another matter.
The 49ers drafted Hyde in the second round and 57th overall. In 20 career starts for Ohio State and 41 games that also included playing fullback, Hyde had 3,516 all-purpose yards, rushing for 3,198 yards on 523 carries.
But playing in Urban Meyer's spread offense is ''completely different'' from Harbaugh's old-school style, Hyde said. He has been focused on learning the pass protection and other nuances of San Francisco's complicated schemes, and by Roman's account, has proven to be a quick study.
Hyde said was looking forward to the team's first contact practice in pads Saturday to show what he does best.
''I'm a hard-nosed runner and a guy who runs with a lot of passion, relentless and refuses to go down,'' he said.
Lattimore was drafted in the fourth round last year after tearing three major ligaments in his left knee in October 2012 at South Carolina. He spent his first NFL season on injured reserve and is still working his way back.
Lattimore was a limited participant in offseason practices but appeared increasingly nimble. He remains on the non-football injury list with knee and hamstring issues.
The 49ers believe Lattimore can contribute at some point this season, and his size and strength - similar to Hyde - fits the 49ers' mold for running backs. But like Harbaugh's staff has done since taking over in 2011, they will use a bevy of backs to give Gore help.
''Thankfully our front office and scouting department had done a great job of building some depth - quality depth,'' Roman said. ''It is not necessarily one person.''
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