USC coach Clay Helton didn't seem overly concerned last Sunday night when he revealed that redshirt senior defensive end Christian Rector was dealing with an ankle injury that prompted his removal late in the Trojans' win over Stanford.

The outlook has changed, though, and Rector is now "really questionable" for the No. 24 Trojans' road game at BYU this weekend.

"He moved around today a little bit better. I think it's more game-time to be honest with you. I think he's really questionable, I'm just being honest with you," Helton said after practice Thursday. "But he did have pads on today, he did move around today, got a good lather, we'll see where it's at tomorrow. He's played a lot of ball -- I think it will be more seeing where he's at tomorrow and on game day. But he's questionable at best."

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Rector (2 tackles for loss, 1 sack, 1 pass batted down, 5 tackles) has played the most snaps of any USC defensive lineman through the first two games, as a fixture at right defensive end in the base packages and even moving to the left side or playing on the interior at times depending on the package.

Freshman defensive end Drake Jackson (3 TFLs, 2 passes batted down, 6 tackles) is a budding star for the Trojans. He's primarily played on the left side and it will be interesting to see how the alignment would change if Rector were out. USC has often pulled a DE off the field and replaced him with outside linebacker Hunter Echols (usually on the right side with Rector moving to the left end), so Echols could be in line for a larger role.

And redshirt junior DEs Connor Murphy and Caleb Tremblay have both been key pieces in USC's defensive line rotation so far and would also be candidates for more snaps if Rector is sidelined or limited. Murphy notched his first career sack vs. Stanford while Tremblay had a half sack in the win.

"We got very fortunate to really have three kids playing good ball last week, as you saw. One was Drake Jackson, the other one was Connor Murphy and then Caleb Tremblay came in and did some really nice things," Helton said. "Those three men did a really, really nice job. If Christian's down, they'll rotate and take it. … We'll keep our same packages."

In other injury news, Helton had a more encouraging report on redshirt freshman DB Chase Williams, who is a top reserve at both nickel and safety. Williams missed practiced earlier in the week with an AC joint injury in his shoulder.

"Chase practiced today, did a nice job. He's going to travel, and I think he'll play in the game right now," Helton said. "But he looked very good today, he felt comfortable today, he said he wants to play. So we'll see how it feels tomorrow, but it did look good today."