Denver Broncos defensive end Derek Wolfe has been suspended for four matches by the NFL for violating their policy regarding performance-enhancing drugs.
The 25-year-old will miss the first four matches of the 2015 season after failing the test, although Wolfe has insisted that his infraction was down to medication which had nothing to do with his displays on the field.
"During the off-season I took a medication which is on the banned substance list," Wolfe said in a statement.
"The medication is not a substance which would enhance my on-field performance in any way and I genuinely was unaware that it was prohibited, but players are responsible for what is in their bodies.
"I will certainly exercise far greater caution in the future and will seek advice relating to the permissibility of any and all medications."
Wolfe has recorded 91 tackles and 11.5 sacks in his three years in the NFL.