A black and white full-frontal picture, which allegedly shows the sportsman in a clubhouse shower circa 1939, is heading to auction in Long Island, New York.

Bosses of the Lelands.com sports memorabilia sale guarantee the photograph is "100 per cent authentic", but DiMaggio's longtime lawyer Morris Engelberg is adamant it must be a fake because the fiercely private star, who was married to Marilyn Monroe, would never have allowed such a saucy snap to be taken.

Engelberg tells the New York Daily News, "When Joe DiMaggio went to the bathroom in a restaurant, I always had to escort him. And I made sure no one took a picture of him at the urinal... I could never imagine Joe DiMaggio, this private individual, ever letting anyone take a photo of him in the nude with someone next to him."

The photo is due to go under the hammer on 24 June (11), but Engelberg warns he "would proceed" with legal action if he finds out the identity of the anonymous seller.