Score this one a big error for House Speaker Nancy Pelosi.

Thursday was the 90th birthday of MLB legend Willie Mays, who played most of his career for Pelosi’s hometown team, the San Francisco Giants.

But Pelosi marked the occasion by posting a photo of herself with another famous Willie, former Giants star Willie McCovey, who died in 2018.

BASEBALL'S SWEETEST SONG: WILLIE MAYS, FOREVER YOUNG, IS 90

"Happy 90th Birthday to an all-American icon, Willie Mays," Pelosi captioned the shot of herself and McCovey, who was a longtime teammate of Mays’ in the 1960s and 1970s and was also feared as a homerun hitter. (McCovey’s wife Estela was also in the photo.)

The speaker’s office, which blamed a staffer for the mistake, soon swapped in a photo of Pelosi with the correct Willie, using the same caption.

Baseball legend Willie Mays is seen in San Francisco, Aug. 19, 2016. (Associated Press)

But sharp-eyed social media users already noticed the error.

"I was half expecting a picture with Orlando Cepeda or something," one commenter wrote, referring to another Giants star of the era.

"Second time’s the charm," another wrote.

CLICK HERE TO GET THE FOX NEWS APP

Mays – who started with the Giants in the 1950s when the team was based in New York, and then concluded his career in the 1970s with the New York Mets -- received numerous well wishes on his birthday, including from retired Yankees star Derek Jeter, retired baseball broadcaster Vin Scully and former President Barack Obama, according to San Francisco radio station KCBS.

During their Hall of Fame careers, Mays smacked 660 homeruns while McCovey hit 521.