Riverside Theatre continued Nicky Henderson's amazing festival with a thrilling victory in the Ryanair Chase.
The 7/2 chance had to dig really deep on the run-in to deny Albertas Run a hat-trick of wins in the Grade One event, giving Henderson a sixth success of the week and jockey Barry Geraghty his fifth.
Tony McCoy asked Albertas Run to make all the running but was hassled all the way by Irish raider Rubi Light, while the eventual winner had anything but a trouble-free run in the chasing pack.
Albertas Run (10/1) still led descending the hill, where Riverside Theatre was upsides for the first time.
Rubi Light was the first to give way but Medermit (8/1) threw down the biggest challenge two out, and may even have led after the last as Albertas Run went right.
But Geraghty got a great response from his partner, conjuring one last lunge to get up close home and deny the brave 11-year-old by half-a-length, with Medermit a similar distance away in third.
"It was hard work," said the jockey. "I never travelled and he missed a good few (fences) but he's game.
"I threw him at the last four fences and he kept coming up. I was beaten everywhere.
"I was a bit tight for room because he wasn't travelling but every time I dug into him he found more.
"I was trying to keep count (of the whip) and I hope I'm all right. He's very classy. It's unbelievable training to bring him back from a year off to win two Grade Ones."
Henderson said: "In fairness that was some great ride. I don't think either of us was enjoying that a lot and I don't think Barry was either as it didn't look very likely all the way.
"They were always travelling a gear higher than he wanted to be in. That was some ride to get him home."
Actor James Nesbitt, who part-owns the horse said: "I just can't believe the ride that Barry gave him and Nicky has done such an incredible job to bring him back like he has.
"The training performance at Ascot was extraordinary, but to have him in that nick today - to have that courage and battle like he did is incredible."
Jonjo O'Neill said of Albertas Run: "He's run a cracking race and we're thrilled to bits with him.
"The ground was maybe a bit on the dead side and AP (McCoy) said that there was one fence on the top of the hill that he didn't really fly, he didn't miss it but just didn't make up as much ground as he might have done.
"He's a great horse to train and I wish I had a yard full of horses like him.
"I thought we were in with a chance and Riverside Theatre was on and off the bridle but Barry gave his horse a great ride, as did AP, but he stayed on. He'll probably go to Aintree if he's OK."
Noel Williams, Alan King's assistant trainer, said of Medermit: "He's run a great race. We'd been thinking about this or the Gold Cup, he stays this (two-mile-five) trip well and I think he'll be worth running over three miles now.
"He's so unlucky not to win here but he's always there or thereabouts."
Poquelin was withdrawn at the start having been kicked in the mouth.
