Flooring Porter won the Paddy Power Stayers' Hurdle, the feature race on day three of the Cheltenham Festival.
Trained by Gavin Cromwell and ridden by Danny Mullins, he produced a bold front-running display to secure the £135,048 first prize.
Sire Du Berlais (5-1) was second, while 2019 hero Paisley Park (9-4f) made late ground into third.
Mullins only claimed the ride aboard the 12-1 winner at the last minute, after his regular jockey Jonathan Moore was injured in a fall at Naas on Sunday.
Flooring Porter set a strong pace throughout and although he made a mistake at the second last hurdle, he kept up the momentum and had three-and-a-quarter lengths in hand at the line.
It capped a remarkable run of victories for the six-year-old, rated just 122 at the start of the season.
"I just had to steer this one, it's special," Mullins said about his first Festival winner.
Moore accompanied Flooring Porter back into the winner’s enclosure.
“I know this lad’s got a massive engine, I rode him this morning and I was too sore, so I said ‘I’ll never do this horse justice", he said.
"I said to Gavin ‘go put Danny Mullins on this horse’s back and he’ll win’. I know how good this horse is and that was not a surprise to me.”
Emma Lavelle, trainer of Paisley Park, said a trip to Aintree or Punchestown is on the cards.
"He's run a big race but he was just beaten by a horse who ran faster than him," she added.
Last year's winner, Lisnagar Oscar, fell at a hurdle down the back straight and was reported to be unscathed.
Flooring Porter is 6-1 favourite with the sponsors to repeat his victory in 2022.
It was another magnificent day for Rachael Blackmore also as she strengthened her lead in the race to be top jockey.
She claimed her fifth victory of the week on Telmesomethinggirl in the Parnell Properties Mares’ Novices’ Hurdle, having earlier in the day won the Ryanair Chase on Allaho.
Like Allaho and Honeysuckle in the Champion Hurdle on Tuesday, Telmesomethinggirl was trained by Henry de Bromhead.
Blackmore said: “It’s overwhelming, to be honest.
“Henry’s done an unbelievable job with her, he always thought a lot of her and she showed it today. She’s got speed as well as everything else, she jumped brilliantly everywhere and she settled better than she had done before.
“I wish I could give you something really good, but I’m genuinely just so overwhelmed by these last few days. It’s all about the horses you’re getting on and I’ve just been so lucky to be riding for the people I’m riding for.”
