OXNARD, Calif. (AP) Cowboys All-Pro guard Zack Martin says he's OK after sustaining a neck stinger in practice earlier this week.

But it's uncertain how many starting Dallas linemen will be available for a preseason game in San Francisco and that might influence quarterback Tony Romo's playing time.

Martin was injured Tuesday in the second of two joint practices with St. Louis at training camp. The second-year player shouldn't be out long.

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The Cowboys are being cautious with left tackle Tyron Smith (right arm muscle strain), left guard Ron Leary (back) and right tackle Doug Free, who recently returned to practice after missing two weeks mostly to rest a sore foot and ankle.

If enough starters sit Sunday against the 49ers, Romo might join them.

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