Say it ain’t so, Mickey.

A corked bat reportedly swung by Yankees legend Mickey Mantle is hitting the auction block – the Mick’s first known doctored bat.

Grey Flannel Auctions is auctioning the Hillerich & Bradsby Co. bat, which was studied by PSA/DNA authenticator John Taube. Taube noticed alterations at the top of the bat’s barrel, and X-rays showed that the barrel had been drilled and filled with cork.

“This is the first corked bat of Mantle that we have seen or heard of,” Taube wrote in his report.

Part of the bat’s handle is coated in pine tar, a characteristic seen on other Mantle bats from the 1960s.

Mantle isn’t alone in swinging a doctored bat. Players have been known to add cork and other substances to bats to improve swing speed, all in hopes of adding extra power to their swings.

But doctoring bats is illegal.

Embarrassing, too. Cubs star Sammy Sosa was suspended for eight games in 2003 after his bat shattered during a game, sending pieces of cork flying.

Last month, a game-used Pete Rose bat that also featured a hidden cork panel sold for $8,000 at auction.

Mantle slugged 536 home runs during his Hall of Fame career with the Yankees, helping the team win seven World Series championships.