Il Etait Temps powered over the line in the Queen Mother Champion Chase to earn trainer Willie Mullins his third win of day two at Cheltenham Festival.
Majborough was the odds-on favourite to claim victory in the big race of the day but a poor jumping display made it an impossible victory.
A mistake at the final fence almost cost Il Etait Temps the win, but jockey Paul Townend steered him over the line at the Festival's first Ladies Day in five years.
"There was a lot of work put into this horse after Ascot so I have a lot of people to thank," Townend told ITV Racing. "It shows how tough this lad is. He's such a courageous horse again today. He was flat as a pan everywhere.
"I wasn't going to force him but he just found his rhythm."
Mullins told BBC Radio 5 Sports Extra: "Out of the corner of my eye I could see Paul Townend thinking 'now we have a horse race'.
"He started to get confident and he planned his move around the last bend."
Libberty Hunter, priced at 50-1, and Sir Alex Ferguson's horse, L'eau Du Sud, finished third.
