Buveur D'Air was made to pull out all the stops to successfully defend his crown in the Unibet Champion Hurdle at Cheltenham.
Nicky Henderson's charge had sauntered to success on his previous three starts this season and was the 4-6 favourite to become the first horse to win back-to-back renewals of the race since Hardy Eustace in 2004 and 2005.
The winner's stablemate Charli Parcs was ridden forcefully, challenging 2015 Champion Hurdle hero Faugheen for the lead for much of the two-mile journey.
It was clear some way from home Faugheen was not travelling with his old zest and in the end it was his stablemate Melon who proved the biggest threat to the reigning champion.
There was little to choose between the pair jumping the final flight and both fought tooth and nail all the way up the hill, but it was Buveur D'Air and Barry Geraghty who emerged victorious by a neck.
Henderson said: "He was tough and what a great race. They've gone a gallop there you wouldn't believe they would keep up in that ground and they have quickened again all the way up the hill.
"Two very brave horses and two great jockeys - I'm sure we got headed at the last and he was brave to come back.
"He had a battle on his hands today and in a funny way that's the first race he's had this year. It's just been in the back of my mind and has always worried me.
"That was the first time he's had to put his head down and fight."
Geraghty, who had to miss last year's Festival through injury, said: "It's real winter conditions, very tacky down the back straight - as it's opened up it's become harder work. The ground made it the ultimate test, there's nowhere to hide.
"He won it the hard way, he battled hard. I tried to save as much as I could on the turn in and go for him as late as possible and he found when it was needed.
"I missed one down the back, which I didn't expect. It was a proper race. The runner-up came and I thought he was coming to beat me, but he's battle hardened. He's as tough as nails and pulled it out.
"Bad luck was the only thing that was going to beat him, and he didn't get bad luck today. He proved there he was a better horse than he was last year. He dug deep and scrapped it out."
He added: "He's very good - you don't win them back to back unless you are very good. He's a top-class horse.
"I missed last season and it's nice to ride a big winner for the boss (owner JP McManus) and doubly to do it for Nicky. It was a long year last year, but I've had great years here so I can't complain."