On Saturday NASCAR suspended Jeremy Mayfield for violating its substance abuse policy. Mayfield immediately rolled out the old "prescribed medicine" defense, saying, "I believe that the combination of a prescribed medicine and an over-the-counter medicine reacted together and resulted in a positive drug test." On Sunday NASCAR fired back with a "liar, liar, pants on fire" response.

NASCAR drug-test administrator Dr. David Black told USA Today, "What we have is a clear violation of policy. In my many years of experience, I have never seen a violation like this due to the combination of over-the-counter or prescription products."

Mayfield is the first Sprint Cup Series driver to violate NASCAR's new drug-testing policy. He has been suspended as a driver and an owner. The suspension was announced three days after former Sprint Cup driver Kevin Grubb was found dead in a Virginia motel room. Police called Grubb's death a suicide. Grubb was suspended by NASCAR in 2006 for refusing to submit to a random drug test.