Isaiah Pead has been suspended without pay by the St Louis Rams for violating the league's policy on substance abuse.
The running back, who had been hoping to fill the gap left by Steven Jackson with the NFC west side, will miss the first game of the 2013 NFL season.
The 23-year-old is eligible to take part in off-season and pre-season activities with the team.
Pead recorded just 54 rushing yards in his rookie season.
