OWINGS MILLS, Md. (AP) - Baltimore Ravens rookie cornerback Asa Jackson has been suspended for four games for violating the NFL's policy on performance enhancing substances.

Jackson has played the past three weeks on special teams after being inactive for Baltimore's first 10 games. He has one tackle.

Jackson, a fifth-round pick out of Cal Poly, will be suspended without pay. If the Ravens make the playoffs, he will be eligible to return to the active roster the day after the team's first playoff game.

His suspension opens a roster spot. The vacancy could be filled by linebacker Ray Lewis, who is eligible to return this week from injured reserve - designated to return. Lewis has been sidelined since Oct. 14 with a torn right triceps.