An original study drawing of a famous illustration by Norman Rockwell sold for $1.68 million Sunday night in Heritage Auctions' Platinum Night Sports auction.

The 1948 study, or preliminary work, for “Tough Call,” which was used as the April 23, 1949, cover of The Saturday Evening Post, belonged to the family of John “Beans” Reardon, an umpire who was the primary subject of the drawing.

“I need to credit my colleagues in the art division for the assist on this one,” said Chris Ivy, director of sports auctions at the Dallas-based auction house. “This isn’t the first time that we’ve been able to draw from other segments of our million-strong bidding clientele to benefit a sports consignor.”

Reardon’s family had believed the original study they owned was merely a signed print, worth only several hundred dollars, Ivy said. It sold to a buyer who wished to remain anonymous, Ivy said.

Sandra Sprinkle, Reardon's granddaughter, inherited the drawing and put it above the mantle of her Dallas home, Reuters reported.

After her death in 2015, her husband, Gene Sprinkle, sold the couple's home and moved to a retirement community. His nephew looked at the drawing and noticed brushstrokes.

"We always thought it was a print, but we hung it over our fireplace because it was signed by Norman Rockwell to Beans Reardon," Gene Sprinkle told Reuters by telephone on Monday.

The drawing is also known as “Game Called Because of Rain,” “Bottom of the Sixth,” and “The Three Umpires.” Rockwell’s finished painting is on display at the National Baseball Hall of Fame in Cooperstown, New York.

The drawing depicts a game at Brooklyn’s Ebbets Field, with the Dodgers leading the Pittsburgh Pirates 1-0 in the bottom of the sixth inning. Reardon and his fellow umpires are looking skyward, debating whether to call the game due to rain.

Gene Sprinkle, 74, said he agreed to let his nephew contact Heritage Auctions, which determined it was an original oil.

"Sandra and her grandfather were very close," Sprinkle told Reuters. "Whenever people came to our house to visit, she was always proud to show it off and tell them about her grandfather."

Sports memorabilia fetched more than $10.7 million during the two-day auction, which ended Sunday, Ivy said.