Saturday was a rough day for the San Francisco 49ers, and it had nothing to do with losing 20-9 to the Houston Texans at Reliant Stadium.

It had everything to do with injuries to RBs Brandon Jacobs and LaMichael James.

First it was Jacobs who left the game in the first quarter with an apparent knee injury, and then James followed with an injury to what appeared to be his left ankle.

James was helping in pass protection in the fourth quarter when his left ankle got mixed up with the feet of OT Derek Hall.

He remained on the field for a few minutes before being helped to the sideline and eventually was carted to the X-ray room.

In a postgame television interview, RB Frank Gore said he wasn’t concerned by James’ injury.

“He’ll be fine. Just talked to him; he said he rolled his ankle,” Gore said. “He'll be fine for the season.”

According to multiple reports, James said he plans to practice Monday.

Harbaugh told the San Francisco Chronicle’s Eric Branch that Jacobs’ injury isn’t season-threatening.

"He’s going to miss a little time,” Harbaugh said. “I don’t think it’s anything that … the ACL’s good. The patellla’s good. It will be some time, but we’ll see. Not something of the you-don’t-come-back-from variety."

Jacobs is expected to undergo an MRI Sunday.

Bakhtiari continues to impress: OLB Eric Bakhtiari was thrust into the starting lineup due to injuries to Aldon Smith and Parys Haralson and made the most of his opportunity. Bakhtiari had a game-high seven tackles and seemed to always be around the ball.

“Eric was playing all out, every snap and was very impressive,” coach Jim Harbaugh said. “He had a couple he’d like to have back, but it was a good step forward for him.”

Bakhtiari spent the last four seasons on several practice squads, but is out of practice squad eligibility. To remain in the NFL, he has to be on a 53-man roster. His performance against the Texans helped that cause.

Mixed results from QB Johnson: QB Josh Johnson entered the game in the third quarter in relief of Colin Kaepernick and immediately made a good impression with a 32-yard pass to rookie WR A.J. Jenkins. The next play, however, he took a step back – overthrowing Jenkins, who created separation deep.

“It should have been a touchdown,” Harbaugh said.

After Scott Tolzien completed 10 of 13 passes last week against the Vikings, the pressure was on Johnson to keep pace with his primary competition for the No. 3 job. His performance didn’t appear to necessarily help or hurt his chances at winning the job.

Follow 49ers reporter Kyle Bonagura on Twitter: @CBSSportsNFLSF and @KyleBonagura.
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