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Denver Broncos quarterback Peyton Manning has been linked to performance-enhancing drugs by pharmacist Charlie Sly in a shocking new Al Jazeera report, "The Dark Side," which was seen by the Huffington Post before it aired.

Sly tells British hurler Liam Collins, who goes undercover in the documentary, that Guyer Institute, an Indianapolis anti-aging clinic, provided Manning with human growth hormones back in 2011 as the former Colt recovered from neck surgery. However, Sly says the company mailed the drugs to Manning's wife, Ashley. Sly since has told Al Jazeera that this claim and others shown in the documentary were "false and incorrect."

Manning's agent told Al Jazeera that Sly's allegations were "outrageous and wrong" and that Manning "has never done what this person is suggesting."

"The treatment he received at the Guyer Institute was provided on the advice of his physician and with the knowledge of team doctors and trainers," Manning's agent added. "Any medical treatment received by Ashley is a private matter of hers, her doctor, and her family."

Manning isn't the only high-profile athlete mentioned in the report, though. MLB veteran Taylor Teagarden talks about his use of performance-enhancing drugs in one of the undercover videos. Meanwhile, Green Bay Packers linebacker Mike Neal is linked to Delta-2, a hormone supplement, by Sly and pharmacist Chad Robertson.

Packers defensive end Julius Peppers, Pittsburgh Steelers linebacker James Harrison, Philadelphia Phillies first baseman Ryan Howard, Washington Nationals infielder Ryan Zimmerman and boxer Mike Tyson also are all linked to Delta-2 by Sly.

Harrison, Zimmerman and Howard denied using the drug, but Neal, Peppers, Matthews and Tyson didn't provide Al Jazeera with a comment.

The documentary airs on Al Jazeera America on Sunday at 9 p.m. ET. You can see a preview of it in the video below.

Click to read the Huffington Post's entire recap of "The Dark Side" >>

Thumbnail photo via Ron Chenoy/USA TODAY Sports Images