The US rider won aboard 'Aggie' while the only Canadian in the competition took second aboard Bardolina 2.
Irish riders continue to be unstoppable this season at shows all over the US; Canada's Erynn Ballard takes overall Hermès Series title.
His Pan Am Games mount Contagious proved the fastest of just three entries who made the jumpoff in the $215,000 Horseware Ireland Grand Prix.
The "Friday Night Stars" feature event was won by the German aboard Drombusch OLD, while Frederic Wandres took the CDI5* GP Special.
The US rider is back in the winner's circle, this time aboard an 11-year-old Oldenburg mare he has been developing since 2021.
The US rider topped the leaderboard with 71.913%; Canada's Ariana Chia made the podium with Guateque IV in the 33-horse class.
Opening day of AGDF 10 in Wellington, FL, saw a field of 16 tackle the qualifier for the GP Special and Freestyle.
The Brazilian rider won the $385,000 Bainbridge Companies Grand Prix aboard Lady Louise Jmen; top Canadian was Kyle Timm, 5th.
The Irish rider and his speedy gelding could not be caught in the $116,000 class, a qualifier for Saturday night's rich grand prix.
The British rider won the $200,000 class riding Point Break and also earned the Leading International Rider award.