The world’s most expensive baseball card has hit the auction block, and sports fans in Manhattan scored a peek at it Friday.

The extremely rare 1909 Honus Wagner — which experts have called the “Holy Grail” of sports memorabilia — is expected to fetch up to $5 million in an online auction ending Oct. 1, said Ken Goldin, founder of Goldin Auctions.

“In the world of sports, it is the single most well-known, iconic symbol in the industry. He was the greatest shortstop of all time,” said Goldin, who put the card on display at the Yankees-themed restaurant NYY Steak in Midtown on Friday.

Only about 50 copies of the uniquely shaped and textured card featuring the Pittsburgh Pirates player were ever printed, Goldin and other experts have said.

In 1911, Wagner demanded that production of the card be halted because it was printed by the American Tobacco Company and sold in cigarette packs, which Wagner thought was bad for kids, Goldin said.

“On the back of the card was a big ad that said ‘tobacco.’ He didn’t want to promote tobacco,” Goldin said.

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