Quevega made history when winning the OLBG Mares' Hurdle for a record sixth year running at Cheltenham.
But the 10-year-old, sent off the 8-11 favourite, was made to work hard by her stable companion Glens Melody until getting her head in front in the final 100 yards.
Ruby Walsh allowed himself the luxury of easing down the amazing Willie Mullins-trained mare in the last few strides.
Glens Melody was beaten three-quarters of a length, with L'Unique the same distance back in third.
Quevega was surpassing the legendary Golden Miller, who won five successive Cheltenham Gold Cups from 1932-36, and did so in her own inimitable style.
Sirene D'Ainay made the running until she came down at the second-last flight.
Meanwhile, Walsh had made eye-catching progress on Quevega, who moved into third place before the final hurdle and set her sights on her stablemate to stride away up the hill and take her place in the record books.
Walsh said: "She's a great little mare and that was the quickest ground she's ran on.
"I was fairly tanking off the home turn and I was thinking I might not get Glens Melody back, but she was good.
"To come back here six times and do it, she's 10 years of age - she has everything.
"It's some performance from Willie to keep bringing her back and minding her and nursing her.
"It's nice to be part of history. When they ask who won the most races at the Festival, it will be Quevega and I can say I rode her.
"I thought going to the last I'd win. Paul (Townend, on Glens Melody) was quicker than I was, but I knew halfway up (the run-in) I was going to get him.
"She's a terrier and she has a wonderful attitude."
Mullins said: "I was delighted for the connections of Glens Melody but I've never been as disappointed looking at what she was beating.
"It was fantastic the way she turned it round in the last 200 yards, she is so brave and keeps pulling it out.
"It's way up there, fantastic. I love Quevega and to do that was one of our missions coming here, to get her there, and I'm happy now for the week.
"She's a superstar. I'm so pleased for her and her connections - she has her own place in history now here."
Asked about a potential bid for a seventh Mares' Hurdle victory in 12 months' time, Mullins said: "We might be too greedy coming back for that.
"We'll have to get her home and think about it.
Townend said: "I'm not sure I'd have been allowed back in the yard if I'd have won!
"My mare has run an absolute cracker and handled the quicker ground no problem."
L'Unique's rider Robert Thornton said: "She's run an absolute blinder and is a good mare on her day.
"Nice ground is the key to her and she also comes to herself at this time of year. She just looked so much better in her skin today.
"I'm trying to persuade Alan (King) to take her to France."