Pre-race 10-11 favourite Flemenstar powered to victory at the Fortria Chase at Navan to deny Big Zeb a fourth consecutive success in the event.
The Peter Casey-trained seven-year-old took the lead from the start and finished seven lengths clear.
Colm Murphy's veteran 9-2 shot Big Zeb exhibited his enduring class to claim second from Foildubh (7-1) at the end.
Cheltenham Gold Cup hopeful Flemenstar's win came on his seasonal debut.
The Andrew Lynch-ridden colt won five of his six starts over fences last season, and he showcased that form from the off as he left his 11-year-old opponent struggling at the back of the pack.
When Foildubh and Big Zeb attempted to close as the horses reached the finish line, he had plenty in the tank to burst clear in the Grade Two meet.
The win saw Flemenstar's odds for the Cheltenham Gold Cup cut with some bookmakers, although others feel he still has to prove himself over a distance of more than two-and-a-half miles.
