Blackstairmountain claimed a famous success for trainer Willie Mullins and jockey Ruby Walsh in the Nakayama Grand Jump in Japan.
The eight-year-old was well beaten on his Tokyo debut when only ninth in the Pegasus Jump, but he stepped up markedly on that form in landing this richly-endowed Grade One contest.
A winner at the highest level at Leopardstown back in December 2011, Blackstairmountain stepped back up in trip to two miles and five furlongs to land first prize in Japan's premier jump race.
Walsh was happy to sit in mid-division in the early stages of the race, steering a wide course before allowing Blackstairmountain to work his way into contention.
Blackstairmountain moved up to challenge the pace-setting Shigeru Juyaku at the final fence and while his Pegasus Jump conqueror Rikiai Kurofune tried to make up ground late in the day, the Irish raider had flown.
He had half a length to spare at the line, becoming the first European-trained winner of the race. Shigeru Juyaku was a further length and a quarter back in third.
Mullins admitted he has had the Nakayama race in his sights for some time.
He said: "I had the Nakayama Grand Jump in consideration back around ten years ago. I had two good jumpers, Florida Pearl and Alexander Banquet-big winners back home-that were invited.
"But when I came out to check out on the conditions here, I decided it wouldn't suit both horses and withdrew the entry.
"I thought it would suit what we call a "summer horse" and it took me a few years to find a horse good enough.
"I had my doubts after Blackstairmountain's performance in the Pegasus but Ruby Walsh, the jockey, was more positive and Emmet and Diarmuid have done a tremendous job in conditioning the gelding for this race.
"I am thrilled and if the horse's condition is fit to come again next time, I would be quite eager to do so."
Walsh felt both the step up in trip and his previous experience of the track had helped Blackstairmountain.
"We were a bit worried about coming back after the Pegasus but the (extra) distance and the experience of the track really helped him and he was a much different horse to ride and it's a thrill to win it," he said.
"After the last fence and coming into the lane when there was a (loose) horse on our outside and the others started to panic, but I was able to position him where I wanted.
"Blackstairmountain likes the fast ground. Unfortunately we haven't been able to have that ground back in Ireland in the last two summers, so we came to Japan for the firm ground and he's shown what he can do in this big race."