Seattle Seahawks starting cornerbacks Richard Sherman and Brandon Browner are facing four-game suspensions for violating the NFL's performance-enhancing drug policy, according to league sources.

Both Sherman and Browner tested positive for Adderall and are appealing their suspensions, insisting they are innocent, according to sources. The appeal could be heard as early as this week.

Upon the team's return to Seattle, the Seahawks released a statement saying they "are aware" of the report.

Seahawks coach Pete Carroll didn't say much about the situation Monday during his radio show on 710 ESPN in Seattle.

"We really can't talk about it at all. It's up to the league and their representation and all that stuff, so we'll just leave it," Carroll said.

The absence of both Sherman and Browner would be a huge blow to the Seahawks (6-5), who dropped a 24-21 decision Sunday to the Miami Dolphins in Miami but still are competing for a playoff spot in the NFC.

Sherman took to Twitter to defend himself, tweeting via his verified account, "This is issue will be resolved soon and the truth will come out. Not worried."

If the suspensions are upheld, Seattle would have to lean on veteran Marcus Trufant to replace Sherman at left cornerback and Walter Thurmond to replace Browner at right cornerback.

Seattle is locked in a race with Tampa Bay (6-5) for an NFC wild-card spot. The Buccaneers have had two starting cornerbacks (Eric Wright and Aqib Talib, who later was traded to New England) suspended for four games for using Adderall.

The 6-foot-3 Sherman leads the Seahawks with four interceptions this season while the 6-4 Browner, a Pro Bowler in 2011, has three interceptions.

If Browner and Sherman are found guilty of violating the league's policy, they would be the fourth and fifth Seahawks players in the last calendar year to be violators. Guard John Moffitt was suspended four games late last season. Reserve offensive lineman Allen Barbre was suspended for the first four games of this season before being released by the team once his suspension was up. And just last week, rookie safety Winston Guy was handed a four-game suspension after taking an over-the-counter product that had a banned substance in the ingredients.

Information from The Associated Press was used in this report.