A broken engine halted McRae's Subaru in mid-Wales, and even emergency keyhole surgery on the car could not bring it back to life. The Scot acknowledged retirement with the succinct comment: "It's knackered."
McRae was leading the rally and on course for a fourth consecutive victory in his home event. He extended his advantage over Burns to 13.8sec on stage 19, but that proved a final, majestic gesture.
Clouds of smoke billowed from the Subaru, and although McRae reached the service point, he sensed the fates that scuppered his championship hopes on the previous rally, in Australia, had pursued him to the last.
Burns, who outpaced the rest of the field on the first three stages of the day to nose in front, could not contain McRae in the afternoon tests, yet now he is on the threshold of his maiden British success.
Carlos Sainz, who needs to finish in the top four today to beat the retired Tommi Makinen to the title, was content to steer a steady course.
Victory for Burns would provide Mitsubishi with some consolation for Makinen's demise and atone for the puncture which checked the momentum of the Englishman and cleared the way for McRae last year.
However, the sense of anticlimax enveloped the entire rally. Burns had relished his head-to-head with McRae, Sainz had wanted to prove himself a worthy champion, and the Subaru camp had yearned for a spectacular farewell by their No 1, who is now bound for Ford.
"The engine's blown up," McRae said. "I don't know exactly what happened, but it's finished. I don't what I've done to deserve this. "We have had to retire on the last two rallies with mechanical problems, and that finished my chances in the world championship. This is not the way to finish the rally or my time at Subaru. I wanted to go out on a high."
Subaru's technical director, David Lapworth, was disappointed that the team and McRae would be parting on such a low note.
"The whole team's devastated," said Lapworth. "We wanted Colin to go out with a win. It's soul-destroying.
Burns had taken advantage of McRae's spins during the morning but then was given rather more assistance than he cared for.
"For Colin to go out like this is a big disappointment for me," said Burns, who earlier this year won the Safari rally. "I know we handed it to him on a plate last year, but we were looking forward to a proper fight for this one."
Sainz prowled around Mc-Rae's Subaru as the crew worked in vain and although the verdict means he is that much closer to a third championship, he echoed Burns' sentiments.
"No one wants a rival to go out with something mechanical," the Spaniard said. "You want to win in good company, that is the best sort of victory. To win at the roadside is not so satisfying."
The organisers also had their headaches at stage 19, Cefn. Spectators spilled on to the track after the first six cars had gone through, causing a hold-up in proceedings. The rest of the schedule was put back 27 minutes.
Burns and Sainz will settle for a straight-forward third day, but they are not yet rid of the McRae threat. Younger brother Alister, in another Subaru, moved ahead of Sainz into second, despite losing his lights, after the Toyota spun off the road on the penultimate stage. Burns led by 65sec.
An anxious Sainz dropped down to fourth, behind Juha Kankkunen's Ford Escort, on the closing stage and Didier Auriol, in the other Toyota, was stopped by clutch problems. Burns returned to rally headquarters 75sec clear of the rest.
Results, Digest, page 29