Un De Sceaux produced his brilliant best under Ruby Walsh to prevail in a thrilling renewal of the Ryanair Chase at the Cheltenham Festival.
The Willie Mullins-trained nine-year-old won the Arkle Trophy at this meeting in 2015, but found a rejuvenated Sprinter Sacre too strong in the Queen Mother Champion Chase 12 months ago.
Beaten after that in the French Champion Hurdle, he has returned at the top of his game this season, recording victories in the Tingle Creek Chase at Sandown and Clarence House Chase at Cheltenham.
Mullins avoided this year's Champion Chase, where stablemate Douvan had been expected to carry all before him, and instead stepped up in trip.
Walsh eventually conceded to let the strong-willed gelding go to the front at the fifth fence and he gave a display of controlled aggression from there, producing a number of spectacular leaps.
Sub Lieutenant did his best to reel him in after the last, but the damage had been done and Un De Sceaux saw it out to score by a length and a half as the well-backed 7-4 favourite. Aso ran a huge race in third.
Walsh said: "I was a passenger. I got him back at the first fence down the back, but he attacked and jumped and he stayed.
"The jump at the last was special. He's a cracking little horse and he's so consistent, he must be a joy to own, he's a little tiger.
"He wants soft ground at two miles which is why we went two and a half miles on better ground.
"It's been a tough year for Willie but he's taken it great, I've worked for him since I was 17 so could eulogise about him all day."
Mullins had uncharacteristically been without a winner on the first two days but has bounced back in style, with this his second big-race winner of the third afternoon after Yorkhill in the JLT Novices' Chase. Mullins and Walsh went on to land the Stayers' Hurdle with Nichols Canyon.
It was also a 50th career winner at the showpiece fixture for Mullins, who said: "He was very keen, I was a little worried with his huge jump at the first but he got him settled. When he saw a line of fences he just went for them, but he sort of settled in front. For him, that's settled.
"He's an absolute iron horse, he's like that on the gallops every day, he wears his heart on his sleeve and I wonder how he can do it without wearing himself out.
"He's so hard on himself, so I'm trying to train him not to do that, this fellow has the button pressed the whole way, I don't know how he keeps the energy and keeps wanting to do it.
"Every time he needed a good jump he got one and I thought it would take something out of the others to catch him. He saved his best jump until last.
"I was confident he'd stay, after the third-last I knew it was bar a fall, I was always confident he'd stay. Any horse who wins over two-four at Auteuil at four should have no problems here.
"As for the King George I don't know if you'd want him doing that over three miles. He can come back to two miles for Punchestown, I'd say."
He added: "We've had a hard few days, but that's the way it is - there wouldn't be any fun in winning over here if it was easy. We take what we get.
"In reality, I suppose Douvan was a huge disappointment and probably not winning the Mares' Hurdle, but then a very good mare beat us in Apple's Jade.
"I think the other horses ran their races and Douvan was probably the only big disappointment."
Part-owner Colm O'Connell said: "It's my birthday today, so this is wonderful
"We've only got three horses with Willie. He's the horse of a lifetime, defeat last year in the Queen Mother to Sprinter Sacre hurt, but we're back with a bang now.
"Ruby is a genius because he lets him do his own thing, he doesn't panic.
"Our job is to pay the bills, they told us he'd stay and that was it. It all makes sense now."
Sub Lieutenant's trainer Henry De Bromhead said: "I'm delighted with him and he ran a cracker. It was a great run.
"I hoped he would get to the winner up the hill, but Ruby Walsh gave his lad a super ride and that's just about it."
Venetia Williams said of Aso: "We are really thrilled as effectively he has come out as the best UK-based two-and-a-half-mile horse. We are really thrilled with what he has done.
"Charlie (Deutsch) was unable to claim his 3lb allowance but he was the man for the job. He rode a fantastic race and was always in the right place at the right time."
Gordon Elliott said of fourth home Empire Of Dirt: "He ran a fantastic race, he was just flat out the whole way round. In a top-class race the trip was too short.
"He will now step back up again in trip, I suspect he will go to Punchestown. There is no point worrying about (running in Ryanair). He has run in the Ryanair and run his race. We have no regrets."