Steelers safety Ryan Clark said he passed a concussion test Wednesday morning, and getting through practice was his second test.

It would seem, then, he's 2-for-2 so far, with a huge final exam on Sunday.

The Steelers take on the defending Super Bowl champion New York Giants in Week 9 in what could be a pivotal game. Sitting at 4-3, and still trying to get past injuries that have plagued them all season, the Steelers have a very difficult assignment in front of them.

It would have been significantly more challenging without Clark, probably the team's defensive MVP through its first seven games. Strong safety Troy Polamalu will miss his fourth straight game, and sixth this year. He played in the opener against Denver and for part of the first quarter against Philadelphia, having to leave with the same calf injury that's kept him out of the vast majority of the season.

Without Clark, the high-octane passing attack of the Giants would have had a significant advantage in the team's greatest strength; big play passing.

The Giants average 282 passing yards and 29.3 points a game. Slowing that offense down is difficult enough, even with Clark.

Running back Jonathan Dwyer did not practice Wednesday, saying he'll be on the field on Thursday. Isaac Redman (ankle) practiced after missing the last two games.