Big Zeb gained revenge on Sizing Europe for defeat at Cheltenham as he edged to victory in the Boylesports.com Champion Chase at the Punchestown Festival.
The pair were neck and neck at the last before Barry Geraghty and his mount Big Zeb powered home by three-quarters of a length from the 11-8 favourite.
Captain Cee Bee, who finished third behind the duo at Cheltenham, had to settle for third place again.
"That was fantastic. I'm delighted for him," said winning trainer Colm Murphy.
Sizing Europe's stablemate Changing Course set the early pace, before dropping off to allow Timmy Murphy's ride to take the lead after four fences.
Geraghty stayed close by until Captain Cee Bee's challenge fizzled out three from home, and the big two slugged it out over the last two fences with 9-4 shot Big Zeb coming out on top despite Geraghty dropping his whip.
"Everything has gone right since Cheltenham and it was especially nice to win here," added trainer Murphy. "He's one in a million, he gives everything.
"I was happy all the way round and I thought Sizing Europe never looked as happy today as he did at Cheltenham."
Geraghty said: "I suppose the spring ground here is that bit fresher and it just helped my fella - he travelled better and jumped better.
"I was always able to sit comfortably behind Timmy but at Cheltenham I couldn't.
"We made a mistake four out and I thought that might knock him back but he was soon on the bridle again.
"He's good and he's gutsy. He's willing to take a chance and Sizing Europe is the same - they don't back off looking for an easy time."