LOUISVILLE, Ky. — Rachel Alexandra has lost again.

The reigning Horse of the Year was beaten in her return to Churchill Downs on Friday, losing a stretch duel to Unrivaled Belle in the $400,000 La Troienne Stakes.

It was the 4-year-old filly's second loss this year, both times as the heavy favorite. Rachel Alexandra was sent off as the 1-5 favorite Friday, but came up short under Calvin Borel.

She was upset in her season debut in New Orleans last month, causing co-owner Jess Jackson to pull her out of a matchup with female rival Zenyatta in the Apple Blossom at Oaklawn Park.

A year ago to the day, Rachel Alexandra won the Kentucky Oaks by an astonishing 20¼ lengths, then went on to beat the boys in the Preakness Stakes.