The 5/4 favourite Snow Falcon gave chase throughout but was held by a length at the line.
Overnight favourite Bapaume (lame) had been scratched in the morning.
Mostly seen over the minimum distance during his career, including in a Grade 1 novice chase victory at Aintree in 2019, the 10-year-old Mahler gelding is showing more reserves of stamina these days having won over 2m4f at Wexford in April.
This was an eighth win of his career, and a sixth over fences.
Winning trainer Henry de Bromhead remarked: "I'm delighted with that and Rachael gave him a super ride.
"It's lovely to see him stay that trip because we have always campaigned him over two miles to two-and-a-half. We just said we'd take the chance stepping him up a bit further and he was really good. Rachael said he saw it out really well.
"He loved the (good) ground and we will consider where to go with him now.
"We will look at these sort of races but I suppose you could consider the Galway Plate as well. Maybe the conditions chase at Galway might suit him better, I’ll see what the owners would like to do.
"I’m delighted for John Phelan and his partner Syed, they’ve had a lot of fun with him over the years."