Buffalo Bills coach Rex Ryan says there's a "real possibility" running back LeSean McCoy will not play against the New York Giants on Sunday because of a nagging injury to his left hamstring.

Ryan said Wednesday before practice that "it doesn't look good." But he won't entirely rule out McCoy from playing.

"Is it worth the time to get McCoy near or at 100 percent again? We're weighing that right now," Ryan said.

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The injury has nagged and slowed McCoy since he was hurt during a joint practice with the Cleveland Browns on Aug. 18. McCoy sat out Buffalo's final preseason games before playing a limited role in a season-opening win over Indianapolis on Sept. 13.

The Bills (2-1) host the Giants (1-2) on Sunday.

McCoy's playing status has been in question since the running back and Ryan acknowledged that rest might be the best option to give the injury time to heal following a 41-14 win at Miami last weekend.

Buffalo is banged up at other positions, too. Ryan said receiver Sammy Watkins' status is uncertain after he hurt his right calf and sat out the final two-plus quarters against the Dolphins. It's also unclear whether safety Aaron Williams will be able to return after hurting his neck in a 40-32 loss to New England on Sept. 20.

McCoy and Watkins won't practice Wednesday, Ryan said.

Though McCoy has played the past three weeks, he has not been the dynamic playmaker the Bills were relying upon n acquiring him in an offseason trade with Philadelphia. McCoy has been limited to 43 carries for 146 yards, and also has seven catches for 83 yards and a touchdown.

That's a considerable drop off for a player who led the NFL with 1,607 yards rushing and 2,146 yards from scrimmage just two years ago.

Following the game at Miami, McCoy complained the injury was acting up and added he "can't really go like I want to."

The Bills lack depth at running back after releasing veteran stalwart Fred Jackson and Bryce Brown over the past month. That leaves Buffalo with two running backs -- rookie fifth-round pick Karlos Williams and Boobie Dixon -- and fullback Jerome Felton on their roster. Receiver and return specialist Marcus Thigpen could also shift to running back.

Another option, Ryan said, is promoting Cierre Wood off the team's practice squad.

Williams has shined while getting extra playing time and helping the Bills lead the NFL with 458 yards rushing. Williams has scored a touchdown in each of Buffalo's first three games. He also had 110 yards rushing against the Dolphins in becoming the first Bills player to top 100 yards since C.J. Spiller had 105 in Buffalo's 2013 season finale.

The Florida State product has also become the NFL's ninth rookie to score in his first three games since 1960.