Does it have anything to do with Ariana's recent gross donut licking episode, where she was caught in the act on video and launched into a mini anti-American rant? You know the one - she was heard saying, "What the f**k is this? I hate Americans. I hate America."
Let's just say that people aren't too happy with her behavior – and, since baseball is as American as apple pie, we're guessing she might not be so well received at the event.
According to a statement released by Major League Baseball (via E! Online), Ariana just had her wisdom teeth removed and can longer meet her obligations.
Demi is thrilled about stepping in last minute, as she's quoted in the statement, saying: "I'm so excited to be headlining the MLB All-Star Concert. I hope my fans in Cincinnati are ready to get 'Cool for the Summer!'"
Tony Petitti, COO, Major League Baseball, commented that "We're disappointed that Ariana Grande cannot partake in the All-Star festivities, but wish her a speedy recovery."
The All-Star Game airs July 14 on Fox.