Kakagh stormed home on the run-in to get up in the dying strides in the beginners chase at Naas.
Robbie Colgan conjured a great finish from the Bill Harney-trained gelding to grab a length success.
15/8f Lucky William looked set to collect after getting on top from long-time leader Loup Du Saubouas only to be denied close home.
"I thought he wanted further than two miles but I said I'd go to Naas as he'd learn a lot," said Harney afterwards.
"It's a good track and a stiff two miles. That was only his fourth run ever.
"We nearly lost him last February. He needed 64 litres of fluid intravenously and we were up all night holding a drip.
"He's a gorgeous horse and we'll take it from here with him."
