Cardinals' Ryan Williams to get second opinion on knee

Arizona Cardinals running back Ryan Williams conceded this offseason that his surgically repaired knee still was just 80 percent recovered when a shoulder injury ended his 2012 season.

Now Williams is battling a "flare-up" in the same knee after an early exit from Sunday's practice.

Camp coverage on NFL Network
Watch "Inside Training Camp" this week from 10 a.m. to 7 p.m. ET on NFL Network.

» Complete training camp coverage

Cardinals coach Bruce Arians looked "unhappy" while discussing Williams' knee Monday, according to The Arizona Republic.

"Ryan's going to get a second opinion," Arians said. "We'll see when he comes back. It just flared up. There's no injury; the MRI's clean."

Williams attributed his reduced ability to push off as "just a little irritation." Arians' frustration stems from the fact that Williams looked good in earlier practices before the "surprise" flare-up.

While the clean MRI is encouraging, Williams' injury history and the need for a second opinion suggest the irritation could linger as a setback.

The pressure is mounting on Williams to avoid a lengthy absence now that Arians has acknowledged 2013 as a make-or-break season for the snakebitten running back. After managing just 2.8 yards per carry in five career games through two years, Williams can't afford to enter the season at less than peak form.

UPDATE: Reporter Darren Urban of the Cardinals' official team site tweeted Tuesday that Williams decided not to get a second opinion on his knee and should return to practice Thursday.