Flemenstar's fitness counted against him on his Navan comeback as he was no match for Felix Yonger in the Grade Two Webster Cup Chase.
Tony Martin's three-times Grade One winner was having his first start for 503 days and made most of the running in the hands of Keith Donoghue.
He still held a slight advantage after the third-last fence, but the tank emptied as the race-fit Felix Yonger took control as Flemenstar faded out of the equation.
Felix Yonger, trained by Willie Mullins and ridden by Ruby Walsh, made a bit of a hash of the final fence, but the 11-10 favourite still had three and three-quarters of a length in hand of Argocat at the line.
Martin said: "He jumped great and it was only from the second-last that he got very tired.
"Flemenstar gave him (Donoghue) a great ride until two out and hopefully he's all right in the morning."
Felix Yonger could now run at the Punchestown Festival.
Mullins said: "I was very happy to see him going on that ground.
"It was very sticky heavy ground and I didn't think he'd go on it.
"The fact that he's won over two and a half miles on that means we could open up in trip more on better ground.
"I'm not sure where he'll go next but he'll get an entry for the Champion Chase at Punchestown.
"He's improving."
Jarry D'Honneur got back on track in the navanracecourse.ie Novice Chase to initiate a double for Mullins and Walsh.
The French import unshipped Tony McCoy in a Grade One at Leopardstown last time but was sent off the 30-100 favourite to make amends in this decidedly weaker contest.
He turned in with a handsome advantage and while he wasn't foot-perfect at the three obstacles in the straight, he still had enough in hand to cross the line with five lengths in hand of Toubaloo.
Sizing Titanium deservedly got his head in front in the Annual Family Day 17th May (C&G) Maiden Hurdle.
Jim Dreaper's seven-year-old had filled the runner-up berth on his previous couple of outings but went one better as the 8-11 favourite.
Paul Flynn's 5-2 favourite Boher Call put in a gutsy performance to take the Follow Navan On Facebook Handicap Chase, leading all the way under Mark Enright and going clear approaching the last before holding Derrychrin's late charge by a head.
All You Need was in a different league to her Irish Stallion Farms EBF Mares Maiden Hurdle rivals.
The 11-8 favourite took up the running before the third-last and although Emily Sinico closed up to within a couple of lengths two out, David Mullins let out an inch of rein and the market leader quickened clear again for a 15-length verdict.
Mullins, who claims 5lb, completed a brace when driving out Bog War (5-2 favourite) to claim the Follow Navan On Facebook Handicap Chase.
