Gatorade says bootleg labels with a picture of Tiger Woods, the word "unfaithful" and the Gatorade name have been found on bottles in Colorado stores.
Gatorade spokeswoman Karen May said Monday the labels were fakes. She declined to say whether the bottles contained real Gatorade.
She says the U.S. Food and Drug Administration is investigating but she declined to say whether any problems have been linked to the bottles. She says consumer safety is the company's top concern.
The FDA declined to comment.
Gatorade sponsors Woods, who has taken an indefinite leave from golf after admitting to infidelity.
May won't say how many bottles were found or reveal what stores they were discovered in.
Gatorade is made by PepsiCo Inc.