SANTA CLARA – Brandon Jacobs made his way through the 49ers' locker room Monday slowly and with the aid of crutches.

Still, the 49ers running back was decidedly upbeat when asked how he was doing.

"I'm doing good," he said without breaking stride. "I can't complain."

That's because Jacobs' prognosis – he'll be out for a few weeks – is a lot better than it seemed after a Texans defensive back took out his left knee in the first quarter of Saturday's loss in Houston.

Jacobs was helped off the field and carted into the locker room. But images taken Saturday and Sunday showed no major damage to the joint.

Teammate Frank Gore said Jacobs probably would miss "a week or two."

Harbaugh, meanwhile, was asked if Jacobs would be ready for the Sept. 9 season opener at Green Bay.

"It's possible," Harbaugh said. "Again, we just have to see how the treatment goes, how the body responds."

Meanwhile, fellow running back La- Michael James, who injured his ankle late in Saturday's game, was walking without a limp Monday. He was not in uniform for the 49ers' afternoon practice, but he was on the field observing the session, and it appears he will not miss any significant time.

If he does, the 49ers have plenty of options.

Although the team leads the league in rushing this exhibition season, its only running back among the top 20 rushers is Kendall Hunter, who ranks 18th. The 49ers have spread the carries among seven rushers, including quarterback Colin Kaepernick, who is tied for fifth on the team thanks to his 78-yard touchdown run against the Vikings.

The 49ers' offense, especially the running game (5.7 yards a carry), is off to a nice start.

Starters return – The 49ers' defense seems to be getting healthy just in time for Sunday's showdown in Denver with Peyton Manning and the Broncos.

Starting outside linebackers Ahmad Brooks and Aldon Smith, who did not play Saturday in Houston, were in uniform for the start of Monday's practice.

Smith, who suffered a hip pointer Aug. 10, appeared to be moving a bit more slowly than his teammates, and he may be eased back into the rotation.

Also in uniform were cornerback Perrish Cox (hamstring) and tight end Delanie Walker, who suffered a knee injury on Aug. 12. Backup outside linebackers Kourtnei Brown (hamstring) and Cam Johnson (knee) did not practice.

Cornerback Chris Culliver was not on the field for the portion of practice that is open to reporters.

More Gore – Gore, whose preseason has been limited to two carries, said he found himself hoping for more work Saturday, particularly after his first carry went for 14 yards.

"When I got out there against the Houston Texans, I wanted to keep running, especially when I got that first carry," Gore said. "That was a pretty good run. I wanted to keep that rhythm and keep going. But I've got to listen to my coach. He knows what's best for me. … Whenever it's time for me to go – hopefully, Green Bay – I'm going to be full speed."

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