SANTA CLARA, Calif. — Mike Singletary's plan for two-a-day practices in full pads from the get-go has his players just a bit nervous heading into the coach's first training camp in charge of the San Francisco 49ers.

Linebacker Takeo Spikes began training twice a day five weeks ahead of time rather than his typical two weeks. Left tackle Joe Staley and the rest of the offensive linemen seriously took their workouts up a notch, too.

"Ready for it to be over," Spikes joked Thursday, when veteran players reported to the team's training complex in advance of the first practice Saturday.

That's when the real grind begins. There's no day off in the practice schedule before the team's exhibition opener Aug. 14 at home against the Denver Broncos.

"I expect it to be physical and intense," said Staley, recently rewarded with a six-year contract extension. "If you know Singletary, he's known for his intensity. ... I feel as strong as I've ever felt in my career."

"I want winners," screams a billboard just up the freeway from team headquarters, featuring a picture of a serious Singletary with arms crossed.

Linebacker Parys Haralson cradled the thick, spiral-bound defensive playbook — "DEFENSE 2009" — under his left arm as he made his way to the lunch tent on a breezy, 78-degree afternoon, when a rabbit scurried across the nearby field turf.

What about rookie wide receiver Michael Crabtree, who could be a holdout come Saturday if he doesn't sign soon.

"Nothing right now," 49ers general manager Scot McCloughlan said.

The record-setting receiver from Texas Tech was the 10th overall pick in the NFL draft by San Francisco after he unexpectedly slipped several slots on draft day.

Singletary, beginning his first full season as head coach after taking over for the fired Mike Nolan last October, is overhauling the 49ers' offense with a philosophy heavily committed to the running game. San Francisco went 7-9 last season and scored only 339 points.

"We made no secrets we're going to be a running team," Staley said. "It's not a boring playbook at all."