The National Football League hit Indianapolis Colts linebacker Robert Mathis with a four-game doping ban on Friday that will sideline him for the first four games of the 2014 season.
Mathis, who led the NFL with a club-record 19.5 sacks last season, will lose almost $US706,000 ($A763,735) of his $US3 million ($A3.25 million) base salary as a result of the ban.
The league and the Colts announced the violation of the NFL performance-enhancing drug policy, which will bench the Colts' top pass rusher for 25 per cent of the season, including a first-game match-up against former Colts star quarterback Peyton Manning and his new team Denver.
"We recognise the extreme seriousness of this matter and will honour the confidentiality requirements of the league's program," the Colts said in a statement on the team website.
"We nevertheless wish to assure Robert and our fans that he remains an honoured and cherished member of the Colts' family and that we support him as he deals with this difficult challenge."
Mathis and his agent claimed after the ban was announced that they would fight the decision by NFL commissioner Roger Goodell because Mathis was taking the fertility drug Clomid.
"We're just amazed that the commissioner and the NFL have levied this punishment against Robert," Mathis' agent Hadley Englehard told ESPN.
"Robert did not follow some of the proper protocol but, to suspend Robert for four games, does not send the correct message."
Mathis, the Colts' main pass rusher, will be eligible to return to the team's active roster on Monday September 29 - a day after the Colts host the Tennessee Titans.
Mathis will also miss the Colts' season opener on September 7 at Denver, where Indianapolis will go against Manning, who guided the Broncos into last season's Super Bowl only to have the team routed by Seattle.
