Undefeated champion Songbird, the heavy early favorite to win the $1 million Kentucky Oaks (G1) at Churchill Downs, will miss the May 6 event due to a fever.

Owner Rick Porter of Fox Hill Farm tweeted out that the Medaglia d’Oro filly came down with a fever after the Santa Anita Oaks (G1) and has started on antibiotics.

“Unfortunately we have to report that Songbird will miss the Kentucky Oaks. She developed a low grade fever after the SA Oaks and has not been able to go out to the track. With the fever not resolved, she was started on a course of antibiotics today, and as a result it'll be another 7-10 days before she's able to return to the track. We are sorry to have to miss the Oaks but what's most important is to get Songbird well, and we have 2 great vets along with Jerry and his team taking good care of her.”

Songbird captured the Santa Anita Oaks (G1) by 3 3/4 lengths for trainer Jerry Hollendorfer. She also won the Las Virgenes (G2) and Santa Ysabel (G3) this year.

The dark bay miss closed out her two-year-old campaign with a romping win in the Breeders’ Cup Juvenile Fillies (G1). She earned an Eclipse Award as the 2015 champion two-year-old filly.

Songbird’s record currently stands at a perfect seven-for-seven and she’s earned $1,982,000 lifetime.