According to his proud mom, Kendall Hunter was an unusually obedient child who only got into real trouble once - something about missing curfew.

But the 49ers' soft-spoken, church-attending rookie running back has always been a bit incorrigible when it comes to his passion.

Consider, for example, what happened when Hunter's coach at John Tyler High in Tyler, Texas, told him he couldn't practice due to an injured shoulder: Hunter, in tears, ran to the locker room, threw on his pads and marched onto the practice field.

Said Hunter, "He couldn't stop me."

When it comes to football, Hunter has always refused to take no for an answer, overcoming a lack of size (he's 5-feet-7 and 199 pounds), a horrific injury (he has a metal plate in his right ankle) and a hardscrabble childhood (his mother, Freddie, worked several jobs to raise three children by herself) to realize his NFL dream.

Now that he's arrived, however, the questions have returned.

Projected as a potential second-round draft pick, Hunter slipped two rounds due to concerns about his size and durability. But the two-time All-American at Oklahoma State who was passed over by a host of bigger-name colleges - nearby Texas among them - remains unfazed entering today's preseason game against the Raiders at Candlestick Park.

"It's nothing but motivation," Hunter said. "I'll work. And I'll learn. And I'm going to get better."

Hunter's no-frills ethos was inspired by his mom, who found jobs at nursing homes, gas stations and churches to raise Kendall, 22, DeNisha, 27, and DeKeith, 30.

Mom set example

Freddie and Kenneth Hunter divorced when Kendall was a toddler, and the youngest member of the family followed his mom's speak-softly-and-get-to-work example.

During a group interview this week, Hunter, setting a standard for brevity, fielded 10 questions in less than three minutes.

"Kendall is sort of like I am, I think, because I'm not really a big talker," Freddie Hunter said. "I mean, if I've got something to say, I'm going to say it. And I know I've got to go to work, so I'm going to go work. And Kendall's pretty much like that, too. He's a doer."

As a junior at John Tyler, though, it appeared Hunter's relentless drive wouldn't be able to overcome an injury that threatened to end his career. During a game against North Mesquite, Hunter's right leg was pulled as he lunged forward. He bounced back up, but immediately fell back down.

His broken ankle was turned sideways, an injury so gruesome that a nearby official became ill. A metal plate and screws were inserted during surgery.

"The first thing the doctor said was, 'I'm sorry, Kendall, you may not play football anymore because this injury is so bad,' " Hunter said. "You may not even walk straight any more. That kind of brought me down, but I prayed, and next thing you know I came back."

Hunter, who returned for spring practice about six months later, rushed for 1,211 yards, earned second-team all-state honors and broke Earl Campbell's school rushing record as a senior to earn a scholarship to Oklahoma State.

Now, after two 1,500-yard seasons at OSU, he's earned positive reviews during his first NFL training camp. Quarterbacks Alex Smith and Colin Kaepernick both have highlighted his work ethic, and two-time Pro Bowl defensive end Justin Smith has taken note of Hunter's moves.

After whiffing on Hunter during a recent practice, Smith told coach Jim Harbaugh that he might have pulled a groin trying to tackle Hunter if he'd been going all out during a game.

A quick study

"He's just so quick and shifty, that's just what I've experienced with him," Justin Smith said. "You think you've got him squared up, and now he's over here. If you just look at him, you can tell he's a quick guy. That's what he can bring to the table. And so far he hasn't disappointed."

Hunter is expected to be a change-of-pace back to complement the power duo of Frank Gore (217 pounds) and Anthony Dixon (233). He's listed behind them on the depth chart but could see significant playing time this season. Gore, coming off a hairline hip fracture, has missed nine games over the past three seasons. Dixon, in his second year, is unproven after averaging 3.4 yards per carry as a rookie.

But the question remains: If called on to handle a larger role, can Hunter withstand NFL punishment?

His spirit certainly is willing. Gore termed him a "tough little dude," and Harbaugh says he has been impressed by Hunter's grit in one-on-one pass-blocking drills, sessions that have produced some of the loudest collisions of camp.

In addition, in tracing his history, it's worth noting that he's been successfully outrunning large and angry pursuers since his early childhood.

Growing up in Tyler, Hunter recalls, his older cousins didn't want him to participate when they played football. So Hunter would wait for the right moment, snatch the ball and take off running.

His mom still laughs at the memory of her well-behaved son's refusal to take no for an answer.

"They would try to make him sit down because he was the youngest and they didn't want to play with him," Freddie Hunter said. "But Kendall wouldn't listen."

Today's game Who: Raiders vs. 49ers Where: Candlestick Park When: 5 p.m. TV: 49ers: Channel: 5 ; Raiders: Channel: 2 Radio: 49ers: 1050, 107.7; Raiders: 1550, 105.3