Holmes was injured in the fourth quarter of the Jets' 34-0 loss to San Francisco. X-rays were negative and additional tests were ordered.
"I'm not sure how many weeks he's going to be out," Jets Coach Rex Ryan said.
"If it's muscle it could heal much quicker, if it's something else -- ligaments -- then it would take much longer. But it's good news that the X-ray was negative. Obviously, it looks doubtful for this week but further than that, I'm not real sure."
Holmes caught four passes for 29 yards Sunday before the injury. He leads the Jets with 20 receptions for 272 yards and one touchdown.
The Jets, 2-2, play the undefeated Houston Texans next Monday in East Rutherford, N.J.
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