Jacobs looked in serious pain on the sideline Saturday. (NFL.com)

On his first run of the 49ers Week 2 preseason game against the Texans, free-agent pickup Brandon Jacobs rumbled for eight yards and suffered what appeared to be a pretty serious left leg injury.

Kareem Jackson hit Jacobs in the left knee and Jacobs ended up on the ground for several minutes before he was helped to the sideline by San Francisco coach Jim Harbaugh.

Jacobs was then loaded on a cart, appearing to be in serious pain, and taken to the locker room. The 49ers haven't announced the nature of the running back's injury, but it's safe to say he won't be returning on Saturday.

We'll let you know when we hear more regarding Jacobs injury, but it certainly didn't look good. On the bright side for the Niners, they have a nice amount of running-back depth, especially if Kendall Hunter turns his preseason performance into regular season success.

Following the game, Jim Harbaugh said that Jacobs "will miss some time," but his injury is "not the you don't come back from variety."

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