Penhill came from way off the pace to come out on top in the Albert Bartlett Novices' Hurdle as Ireland continued to dominate at Cheltenham.
Successful with Arctic Fire in the County Hurdle earlier on the card, Willie Mullins was winning his sixth race of the Festival and Paul Townend his second.
Ami Desbois did the donkey work to two out but there were soon just three vying for victory with Penhill, Monalee and Wholestone taking over.
The latter was the first to crack and try as Monalee could, Penhill (16-1) held the aces as he powered up the hill to win by three and a half lengths. Wholestone was four lengths away in third.
Townend said: "He's a class horse, we kept him wide to get into a rhythm.
"I won on him over three miles at Christmas at Limerick on heavy ground and he saw it out really well."
Owner Tony Bloom, chairman of Brighton & Hove Albion Football Club, said: "I'm over the moon for everyone involved, it was a great ride by Paul and it's a brilliant horse we have here.
"He was looking good all the way and two out we were expecting him to win, his hurdling was a lot better than it has been and he's got the pace.
"Racing over three miles has been the making of him, as it gives him more time for his jumping.
"I haven't had many Cheltenham runners, so it is very exciting. I've brought a lot of friends and they're all on at 16 and 20-1."
Mullins said: "It's not a race that has been lucky for us. It's been a great day for Paul with two winners. Penhill has class. We were trying to win with him over two miles, but he just couldn't handle the pace of top-class races over two miles.
"We put him up to three and he did it easily at Christmas, then we said we would go for this race.
"He will go to Punchestown now and he is a horse that could go back on the Flat. He could be a Melbourne Cup horse.
"Maybe he won't be good enough when we go back and try the Flat but we will see. He has got a typical profile for the horses we manage going back to the Flat.
"They are just going two or three miles an hour slower over three and it just gives his brain time to work and get him in the right order jumping."
Henry de Bromhead said of Monalee: "I'm delighted with him, he ran a great race, we were just beaten by a battle-hardened horse unfortunately, and a very good horse.
"We'll look forward to going over fences with him next season, that should be exciting. We'll get him home and see how he is before we decide if he runs again."