Tampa Bay's defense was jolted Saturday when the NFL suspended cornerback Aqib Talib four games without pay for violating the league's policy on performance-enhancing substances.

The fifth-year pro said in a statement released by the team that he took an Adderall pill without a prescription "around the beginning of training camp." He will not appeal the ban, which begins Sunday against the Kansas City Chiefs.

Talib was the 20th overall pick in the 2008 draft and is one of the team's top defenders with 18 career interceptions. He also will miss games against New Orleans, Minnesota and Oakland, becoming eligible to return to the active roster Nov. 5, the day after Tampa Bay faces the Raiders.

"I have spoken with Aqib, and he knows that he made a poor decision that let our team down," Bucs first-year coach Greg Schiano said. "Certainly, other players will have the opportunity to step up while he serves this suspension."

It's the second suspension of Talib's career.

Talib suspended without pay for the 2010 regular-season opener and also fined one additional game check for violating the NFL's personal-conduct policy. That discipline stemmed from an altercation with a St. Petersburg cabdriver during training camp in August 2009.

"I made a mistake by taking an Adderall pill without a prescription. This is especially regrettable because, for the past several months, with Coach Schiano's help, I've worked very hard to improve myself -- professionally and personally -- as a player and a man," Talib said.

"I am truly sorry to my teammates, coaches and Buccaneers fans, and I'm disappointed in myself. I will work diligently every day of this suspension to stay in top football shape and be ready to help this team in the second half of the season," Talib added. "I have chosen to be immediately accountable for the situation I put myself in, which is why I will not exercise my appeal rights and will begin serving the suspension immediately."

The Bucs placed Talib, who has one interception and a team-leading seven passes defensed, on the reserve/suspended list. Defensive end Markus White was promoted from the practice squad to fill the roster opening. There was no immediate announcement on who'll replace Talib in the starting lineup.

Fourth-year pro E.J. Biggers, who sat out the first three games of the season because of injury, and seldom-used third-year pro Myron Lewis are listed behind him on the depth chart.

Browns: Cornerback Joe Haden believes his return Monday from a four-game suspension for violating the NFL's policy on performance-enhancing drugs has given the team renewed energy that could pay off when it hosts Cincinnati on Sunday.

"I could tell out there at practice," Haden said. "I don't know how it was when I wasn't here, but since I'm back, we're up, just amped. We're hyped."

Colts: Four-time Pro Bowl defensive end Robert Mathis and starting running back Donald Brown did not make the trip when Indianapolis traveled to New York on Saturday for its game against the Jets. The Colts had said both would miss two to three weeks with knee injuries.

Linebacker Jerry Hughes is expected to replace Mathis in the starting lineup, while rookie Vick Ballard is slated to make his first NFL start in place of Brown.

The Akron Beacon Journal contributed to this report.