ALAMEDA, Calif. (AP) -- Amari Cooper disputed Josh Norman's comments that the Raiders wide receivers were taunting the Redskins defense before last Sunday's game in Washington and said he's uncertain what the veteran cornerback was referring to.

Norman lashed out at Cooper and Michael Crabtree in a lengthy postgame tirade after the Redskins handed the Raiders their first loss of the season and accused Oakland's star receivers of talking trash beforehand.

"What was personal, other than them getting their tails whupped?" Norman said. "I mean, first and foremost, you don't come up in here and say what you're going to put up on somebody. Two hundred yards? (Crabtree) didn't catch two balls. He only caught one, huh? So please, whatever you do, do not run your mouth if you're a wide receiver and expect to show up on Sundays, because I'm telling you, we are here and we are waiting."

Crabtree declined to talk to reporters Wednesday but Cooper did and sounded confused by Norman's comments.

"I don't know where he gets that from," Cooper said. "As long as I've been here I've never bragged or anything before or after a game. I don't know where that comes from."

More concerning to Cooper is getting his season on track following a rough start. The fourth-overall draft pick in 2015 has caught only 10 passes through three games and is coming off one of the worst outings of his career after being limited to one catch for six yards by the Redskins.

It was only the fourth time in his career that Cooper has failed to catch more than one pass. Two of the others came during his rookie season.

Cooper dropped a pass on Oakland's first possession of the second quarter, continuing a troubling trend that also plagued Cooper in his rookie season. He had four drops in the Raiders' season-opening win against Tennessee and has an NFL-leading six overall, according to Pro Football Focus.

"I try to move forward," Cooper said. "Obviously I like to look back on them and see how I dropped the ball and then try to fix it. Most of the balls that I've dropped have been from a result of trying to run before I actually catch the ball. It can be a little frustrating but just have to go and fix it."

Raiders quarterback Derek Carr didn't sound too concerned with Cooper's slow start.

"Whenever those kind of things happen you move on but you have to address it . because it needs to be better," Carr said. "I don't think he's pressing or anything like that. He expects so much more out of himself that he gets mad at himself."

Neither Cooper nor Crabtree were factors in the Raiders' loss to the Redskins. Crabtree was also held to one catch and left the game in the fourth quarter with a chest contusion.

Raiders coach Jack Del Rio sounded optimistic that Crabtree will play Sunday in Denver. Crabtree and Cooper (knee) were limited in practice Wednesday.

"We'll see how the week goes," Del Rio said.

Notes: First-round draft pick Gareon Conley (shin) was held out of practice. Running back Jalen Richard (calf) and safety Keith McGill (foot) were limited.