The Big Dog opened his account over fences after coming out on top in a thrilling climax to the Punchestown Grand National Trial.
Peter Fahey's charge had been placed in his first three completed starts in novice company over the larger obstacles, most recently finishing third when a hot favourite at Navan last month.
Entering handicap company for the first time since his hurdling days, The Big Dog was the 5/2 market leader for Punchestown's 80,000 euro feature, with top amateur Jamie Codd in the saddle.
The eight-year-old travelled with more zest than many of his rivals for much of the three-and-a-half-mile journey and looked likely to win comfortably after kicking clear rounding the home turn.
However, Screaming Colours finished to good effect in the testing conditions and made The Big Dog pull out all the stops to claim victory by half a length.
Fahey said: "His runs in all his beginners' (chases) were good after coming back from a year off. I'm delighted for the Kellys (owners), as they are huge racing supporters and its great for them to win a good pot.
"He'll tip away in good handicaps and see how it goes. He's lairy and you have to make plenty of use of him, which is tricky in beginners' chases as when you force it in front, he's losing ground jumping.
"His jumping was brilliant today until he took it up and he just looks around."
Considering future targets, the trainer added: "If the ground was heavy we might think about the Irish Grand National, but he'll probably need to go up a bit in the weights to get into it. We'll see when the time comes."