Enable has had to call on all her reserves to fight off Crystal Ocean and become only the third dual winner of the King George VI And Queen Elizabeth Stakes.
Sent off the 8-15 favourite for the Ascot showpiece, the John Gosden-trained mare found herself trapped wider than ideal through the early stages under Frankie Dettori as Norway led the pack.
After Derby winner Anthony Van Dyck became the first of the big guns to drop away, Crystal Ocean and Enable swung into the straight full of running with Dettori calling on Enable for her effort at the two-furlong (400m) marker.
Crystal Ocean and James Doyle refused to buckle, and the prize looked up for grabs before Enable and Dettori got the last word to win by a neck.
Waldgeist was third, another length and a quarter away.
"She's everything you ever want," Gosden said.
"The draw (11) rather affected her. She was suddenly very wide, so Frankie dropped back further than he wanted.
"She's a brave and wonderful filly, and what a great battle with Crystal Ocean.
"It's what you wanted to see.
"I think she possibly carried him (Dettori) into the race a little too easily, and I thought he'd hit the front a long way out, but he felt he had to go then.
"Crystal Ocean showed all the courage in the world, and the first two are wonderful - they put up a great King George.
"It was a great race, it's what it's all about."
All roads for the Khalid Abdullah-owned winner, who won the race in 2017, lead to a Prix de l'Arc de Triomphe hat-trick bid in October, and Gosden will give further consideration to how she gets there.
Revelling in the latest big-race success of a season that has been extraordinary even by his standards, Dettori was full of praise for Enable.
"I'm carrying the pressure of the nation. She is unbeaten for two years," he said.
"Not only is she a super mare, she showed what a courageous will to win she has. I don't want too many races like that, as I'm absolutely exhausted.
"In all my career it is probably the hardest and most hard-fought race I've ever had. It was two great champions. Give credit to Crystal Ocean, he put it out there for me and it was an amazing race.
"We are on the road to Longchamp now."
Crystal Ocean's jockey James Doyle the race was an amazing experience.
"I've never experienced finishing second in a race and getting as loud a cheer as the winner," he said.
"They really do love him and he wears his heart on his sleeve. What a run. It was a great race, it was unbelievable.
"She joined me and it felt like I headed her back - well I thought I did - and I thought we could be in business, but she just digs into the reserves and away she goes.
"Credit to my fellow, he left every inch of his heart out on the track there."