After two winners earlier in the day to add to his treble on Tuesday all the signs pointed to red-hot favourite El Fabiolo bringing up the century for
But a horrendous error put paid to El Fabiolo's chance, leaving Jasmin De Vaux to claim his place in history as Mullins's 100th winner in the day's closing bumper.
"Unbelievable - certainly when I had my first winner here around 30 years ago I thought that was my lifetime achievement.
"Who ever thought any trainer never mind me could do it! Extraordinary stuff."
Mullins, who won Tuesday's Champion Hurdle with State Man, still has plenty to look forward to over the next two days, not least on Friday with his defending Gold Cup winner Galopin Des Champs.
Not that he will have needed reminding but El Fabiolo's misfortune half an hour earlier proved how the sport of kings can be full of hard knocks along the road to success.
Mullins' contender was sent off at 2-9 - the shortest priced favourite since Flyingbolt won this race back in 1966 at 1-5.
His cramped odds were in part due to the morning defection of his principal rival, Jonbon.
On paper that left El Fabiolo only having to turn up to win - but that was counting without the most crucial aspect of the sport - jumping.
Under
That knocked the stuffing out of him with Townend pulling him up and his legion of backers counting their losses.
With El Fabiolo out of the picture it left the stage to the brilliance of Blackmore, a Gold Cup winning jockey and already off the mark this week, to plot her path to victory on last year's runner-up.
Frontrunner Edwardstone fell when in the lead after the turn for home leaving Captain Guinness to hold off El Fabiolo's stablemate Gentleman De Mee for an unexpected but nonetheless welcome win.
'Anything can happen'
"Rachael's such an incredible rider," said winning trainer Henry De Bromhead, who was adding to his previous Champion Chase wins with Sizing Europe, Special Tiara and Put The Kettle On.
Realistically de Bromhead was not expecting to be in the winner's enclosure - even though the winner finished second in the race last year - given El Fabiolo's form as the horse to beat.
"We were hoping he'd just run well," said the Irish trainer.
"I've always said he deserves a Grade 1, and anything can happen - it's a horse race."
Before El Fabiolo the Mullins machine marched on and the 67-year-old produced a notable achievement even by his high standards when training the first five home led by hotpot Ballyburn in the opening Grade 1 novice hurdle.
Also grabbing the spotlight on Wednesday was
