The thoroughbred, aptly named Gronkowski, won the Burradon Stakes in England on Friday, qualifying the Kentucky-bred colt for the venerable May 5 race at Churchill Downs.
For the first time, the race is allotting one spot in the 20-horse field to a European-based horse. Trained by Jeremy Noseda and ridden by Jamie Spencer, Gronkowski moved ahead of Mendelssohn on the European Derby leaderboard.
"We've had this dream, and now the dream is alive," Noseda told At The Races after the horse's victory.
Gronkowski (the football player) has attended The Run for the Roses in the past, taking in the sites and sounds of Millionaires Row alongside teammate Tom Brady and others.
Kerri Radcliffe of Phoenix Thoroughbreds, which owns the horse, said his height -- the same as the Patriots star (6-foot-5) -- and size of the horse made it an appropriate name.
"I love the New England Patriots, and as Rob Gronkowski is 6-5 and about the same wide, I thought it would be an appropriate name for the horse, as he's built much the same," Radcliffe told the Racing Post last month.
Gronkowski (the horse) has finished first in his last four races, with two victories coming in March.
"It sounds strange, but I haven't yet seen on the racetrack what I believe this horse is capable of. I'm sure there's more to come," Noseda said.
Mendelssohn will try to qualify for the Kentucky Derby through the main Derby leaderboard with a victory Saturday in the UAE Derby. Another spot in the Kentucky Derby field is being allotted to a Japan-based colt.
ESPN's Darren Rovell and The Associated Press contributed to this report.