PROVO — It's a different injury, but a similar situation for BYU's Fui Vakapuna.

The senior running back was slowed last year in the wake of undergoing ankle surgery after the 2006 season. Then, he was sidelined for three games during the 2007 campaign due to a hand injury.

Meanwhile, Harvey Unga burst onto the scene to rush for more than 1,000 yards and earn Mountain West Conference freshman of the year honors.

Last spring, Vakapuna said he thought he had something to prove coming into the 2008 season. But once again, he's been hampered — this time by a lingering hamstring injury. Vakapuna sustained the injury in June while running for pro scouts. So far during fall camp, he has been limited in his participation in drills.

"It's progressing," Vakapuna said of his hamstring, adding that he spends an hour prior to practice warming up his hamstring. "I'm taking it day-by-day."

He added that he's close to being full strength.

"I've been going full-speed during warm-ups," he said. "Sometimes (the hamstring) tightens up here and there. I'm getting treatment and making sure I can stay healthy. ... I've been slowly but surely coming along. I'm almost to full speed to where I can explode and make good cuts."

Vakapuna's health has taken on even more importance since fullback Manase Tonga was suspended for the season back in June.

"Manase was a vital part of our offense," Vakapuna said. "He was basically the heart of our running backs corps. It changed a lot of our mentality. We need to find players who can step up and take up that position to help out. We're getting there, seeing the progression of our fullbacks that are stepping up."

To this point, freshman Bryan Kariya, a Davis High product, is getting plenty of action at fullback, along with another freshman, Kaneakua Friel, a tight end. Friel, who stands 6-foot-5 and 240-pounds, has impressed coaches and teammates.

"Friel is doing well," Vakapuna said. "He made a big hole for Harvey (during a non-contact drill). A lot of rookies mess up, but he's doing well."

Still, Vakapuna has his sights on claiming Tonga's spot at starting fullback.

"Definitely. I have to," he said. "With the experience of me and Harvey, it's the only way we can go. It's the only car we're going to use. Playing fullback is a better opportunity for me to help out and do whatever I can do to help the team move and be more consistent and efficient."

Vakapuna rushed 73 times for 252 yards last season, with 97 of those yards coming in the regular-season finale at San Diego State.

On Monday, BYU coach Bronco Mendenhall took Vakapuna to task publicly when asked about Vakapuna's status.

"I wasn't too happy with how he looked today," Mendenhall told reporters. "It might take longer than expected (for him to compete).

"That's unfortunate. A lot of times, though, that's traced to how vigorous a player goes after the rehab and how diligent they are in the summer time. My guess is, knowing that I can't keep track of it, it probably wasn't as diligent as necessary."

Vakapuna said he worked hard during the summer and came into camp in good shape.

"I've been here all summer long and all spring trying to get things done physically," he said. "I'm pretty happy with the kind shape I'm in right now. But I know I can get better."