Tennessee Titans and former Michigan offensive lineman Taylor Lewan is claiming his innocence after he tested positive for a banned substance recently.

According to a report from ESPN’s Adam Schefter, Lewan provided a sample that tested positive for ostarine over the summer. His Sample A tested positive but his Sample B has not come back from testing yet.

If Sample B also comes back positive, Lewan would face a four-game suspension from the NFL.

Lewan maintained his innocence in an emotional Twitter video he posted on Wednesday. In the video, the Titans left tackle claims that he did not knowingly take any banned substances and has never “cheated the game.”

The positive test comes one season after Lewan became the highest-paid offensive lineman. He signed  a five-year, $80 million deal, which included $50 million in guaranteed money.

Below is the video posted by Lewan. He plans to appeal the results.