Ingrid Andress Says She Was Drunk During Home Run Derby Anthem, Going To Rehab

Country music star Ingrid Andress is owning up to her now-infamous national anthem at Monday night's Home Run Derby ... admitting she was hammered during the performance.

Andress faced the music hours after her rendition was widely panned on social media ... going to Instagram to explain why things went so awry.

"I'm not gonna bulls*** y'all, I was drunk last night," Andress said in a statement. "I'm checking myself into a facility today to get the help I need. That was not me last night."

Andress also extended an apology to Major League Baseball, sports fans and the entire country for her performance.

"I'll let y'all know how rehab is I hear it's super fun," she added.

As we previously reported, Andress gave Fergie a run for her money as one of the worst "Star-Spangled Banner" renditions in recent years ... as her crooning was all over the place and off-key.

It was so bad, Derby participants appeared to be holding back giggles throughout the song ... and once it was over, the fans in attendance were far from supportive.

Many questioned what the heck happened -- as Andress is a well-known, established artist in the industry.