Alabama and Clemson could be missing players for disciplinary reasons in their College Football Playoff semifinal games on Saturday.
Alabama suspended the starting left guard Deonte Brown and two other players from the Orange Bowl for violating unspecified team rules, and Clemson Coach Dabo Swinney said the star defensive tackle Dexter Lawrence and two other players had failed N.C.A.A. tests for performance-enhancing drugs and might not play in the Cotton Bowl.
Crimson Tide Coach Nick Saban said in a statement that Brown, tight end Kedrick James and offensive lineman Elliot Baker had not made the trip to Miami on Monday with the rest of the team.
Top-ranked Alabama faces Oklahoma on Saturday night in a semifinal game.
Saban did not indicate how long the suspensions would be or whether they might extend to the national championship game, on Jan. 7, if Alabama wins on Saturday.
Brown, who replaced Lester Cotton as the starter in midseason, has been dealing with a turf toe injury.
Swinney said at a news conference that the N.C.A.A. had informed Clemson that trace amounts of ostarine had been found in samples given by Lawrence, the reserve offensive tackle Zach Giella and the freshman tight end Braden Galloway. Ostarine, also known as enobosarm, is used to treat osteoporosis but can also act like an anabolic steroid.
Swinney said the players had told him they had not intentionally taken the substance. Clemson, which faces No. 3 Notre Dame in the Cotton Bowl, is awaiting results of a second sample from each player. The N.C.A.A. ban for failing a test for performing-enhancing drugs is one calendar year.