Siskin overcame a troubled passage to ultimately power to victory in the Tattersalls Irish 2,000 Guineas at the Curragh.
The unbeaten Ger Lyons-trained colt was locked in a pocket on the rail with two furlongs of the mile Classic to run, but Colin Keane managed to get a run and once in the clear his mount quickened smartly to the front.
In what was a rough race, Aidan O'Brien's Vatican City also finished to some effect but was a length and three-quarters away from the winner. Lope Y Fernandez, who got first run and looked like being the winner at one stage, was another three-quarters of a length back in third.
Owned by Khalid Abdullah, the 2-1 favourite provided Lyons and Keane with a first Classic success and added to his Group One victory in the Phoenix Stakes over six furlongs at the Curragh as a juvenile.
Lyons said: "This means everything, it means 30 years' hard graft for everybody - to win a Guineas was always my number one and hopefully it's the first of many.
"I'm delighted with the support we are getting from owners and the quality has increased year on year. That was hard work and full credit to Colin Keane. You don't get a Guineas handed to you and they both stood up when it was needed. If there was a kink in that horse then he wasn't going to go through that gap.
"Colin is the best there is at the minute. He's only a kid and he's going to keep improving.
"I also want to thank Khalid Abdullah, who is watching in Paris I'm sure. They are the ultimate breeders."
Siskin had never previously run beyond six furlongs, and Lyons went on: "I was worried about this horse's trip around February and March, but when we went into lockdown then I was confident that the trip wasn't an issue. If we were a sprinter then we were in trouble because we weren't quick enough.
"He's a very easy horse to train and no question he's the best I've trained.
"We'll probably go to Goodwood next for the Sussex, but I want to keep Colin on him and hopefully the 14 days (quarantine) will be gone by then. We are definitely skipping Ascot.
"We'll have a chat about it, but that was the plan providing he was good enough today.
"I know he gets the mile and I wouldn't draw a line through 10 furlongs at the moment."