Willie Mullins was out of luck as the former Irish-trained Rawnaq beat Shaneshill and Nichols Canyon in the Calvin Houghland Iroquois Hurdle in Nashville, Tennessee, on Saturday.
The race is part of the Brown Advisory Iroquois Cheltenham Challenge which involves the Ryanair World Hurdle and the Tennessee race. If any horse can win the two three-mile Grade Ones within 12 months connections would earn a $500,000 bonus.
Nichols Canyon, third to Annie Power in the Champion Hurdle and Aintree Hurdle, disputed it from the off alongside Rawnaq, but Ruby Walsh sent out the distress signals rounding the home turn, as Shaneshill emerged as the biggest threat to the leader.
The versatile Shaneshill, second in the RSA Chase at Cheltenham and occupying the same position in the Stayers' Hurdle at Aintree before falling at Punchestown, gave admirable late chase under Danny Mullins but, while he closed all the way to the line, Rawnaq just held on.
Now trained by Cyril Murphy, Rawnaq was a six-time winner in Ireland for Matthew Smith.
America remains unconquered by Mullins to date, although he has won the Grand Nakayama Jump in Japan with Blackstairmountain in 2013.
Mullins' father, Paddy, won the Dueling Grounds International Hurdle in Kentucky with Grabel in 1990.
Doyle, whose father Pat was among the crowd of 25,000, won the 2015 Iroquois on Demonstrative.
Connections of Rawnaq indicated that the horse may be aimed at the 2017 World Hurdle at Cheltenham.
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