According to numerous sources, including the Daily Racing Form, 2014 Kentucky Derby winner and Horse of the Year California Chrome is out of the Arlington Million.
The DRF reported on Sunday that trainer Art Sherman said California Chrome is unlikely to race again in 2015 after being diagnosed with a bruised cannon bone.
California Chrome has been stabled at Arlington since Tuesday, when he arrived back in the United States from England.
His connections were hoping to race Chrome in the Aug. 15 Arlington Million.
Sherman reportedly said the horse would be fine and that it is not a life-threatening injury.
California Chrome's owners shipped the 2014 Horse of the Year to Arlington namely because of its location, turf surface and attraction for fans.
Arlington marketing director Howard Sudberry had said the Million was always on the owners' radar.
"Perry Martin (one of the owners) is a Chicago native, so it was obviously attractive to him and made him want to run his great horse here," Sudberry said a few weeks ago. "They really relished the opportunity to show him off in a different part of the country.
"Also, the Million is a turf race. Last December, Chrome ran in the Hollywood Derby and won it easily, showing he can handle a grass race just fine."
California Chrome would have been the most well-known horse to race at Arlington in quite some time.
Arlington's history is dotted with legends such as Spectacular Bid, Cigar and Secretariat, though only one Kentucky Derby winner has run in the Million -- Gato Del Sol in 1984.