ALAMEDA -- Rookie cornerback DJ Hayden missed practice Thursday with a groin strain and is no lock to play for the Raiders against the New York Giants.
Dennis Allen said Hayden was injured during Wednesday's practice, but the Raiders coach didn't find out about until after he was done talking with the media.
"We'll have to evaluate him and see how he's doing and see how quickly that thing responds," Allen said.
The Raiders play the Giants on Sunday at MetLife Stadium.
Hayden said Wednesday that he was looking forward to getting back on the field after giving up three receptions for 139 yards and two touchdowns in coverage in a 49-20 loss to the Philadelphia Eagles.
The Raiders' nickel cornerback, Hayden plays on the outside with Tracy Porter moving into the slot when opponents use three receivers. The Giants have three wide-receiver sets featuring Hakeem Nicks, Victor Cruz and Rueben Randle.
If Hayden can't play, Phillip Adams will be the nickel corner. Adams had two interceptions for the Raiders last season when pressed into action because of injuries.
"We've got all the confidence in the world in P.A.," Allen said. "When he came in last year and had an opportunity to play, he played real well. That's been an easy transition for us."
Jennings subbed for Darren McFadden in the second quarter and finished with 102 yards on 15 carries. He'll likely be the feature back against the Giants as McFadden missed his second day of practice with a hamstring strain.
"Like I always tell you guys -- you're called to duty, you go make plays," Jennings said. "Regardless of that, the outcome was we lost. (We) didn't do enough. However you slice it or dice it, we go out there to win."
Jennings has remained consistent with that theme since he arrived at training camp. He repeated it to students during a community outing Tuesday.
"One thing I left them was, when I was in high school, I always kept a quote, 'When opportunity presents itself, it's too late to prepare for it,' " Jennings said. "So every day, be prepared to be that guy."
Quarterback Terrelle Pryor said, "We saw Rashad make a lot of guys miss and run over a lot of guys. We're definitely going to miss Darren because he may miss the game, but I have a lot of trust in Jennings and I believe he can get the job done."
Jennings has also been a mainstay on special teams, blocking two punts, as well as recovering an onside kick to seal the win over Pittsburgh.
Through eight games, Reece has 13 carries for 57 yards and 12 receptions for 108 yards -- 25 touches for 165 yards and one touchdown.
Last season, Reece had 59 carries for 271 yards and 52 receptions for 496 yards in 16 games -- more than double the workload on a per game basis.
Pryor said part of the reason is opponents are defending Reece with a cornerback on pass routes.
"A corner on Marcel, not to say he can't do it, but it's very tough," Pryor said. "Marcel is a great matchup versus a linebacker or a safety, and we're not really getting a lot of those looks."
Sebastian Janikowski (ribs) was limited, got in some kicking and will play. Guard-center Andre Gurode (knee) was limited, and Allen isn't sure if he'll reclaim his left guard spot from Lucas Nix.