Neil Fachie and Barney Storey won Great Britain's third gold medal of the Paralympic Games track cycling programme with a scintillating display in the tandem one-kilometre time-trial at the London 2012 velodrome - but there was mechanical heartache for Anthony Kappes and Craig MacLean.
Fachie, who is partially sighted and competed in athletics in Beijing in 2008, and pilot Storey clocked a world record of one minute 01.351 seconds.
Kappes, who won the event in partnership with Storey in 2008, and MacLean suffered two mishaps and were denied a third opportunity to start by race officials. The duo, world champions in February, had been scheduled to start last, but two chain failures saw their competition come to an end.
Spain's Jose Enrique Porto and Jose Antonio Villanueva took silver in 1:02.707, with Ireland's Jason Brown and Damien Shaw ninth in 1:07.979.
Fachie paid tribute to the support of the crowd as he and Storey closed in on their record-breaking time.
"The atmosphere was electric," he said. "The crowd pushed us round that final bend. I just can't believe it. To be here winning the gold medal is a dream come true."
Storey echoed Fachie's appreciation of the home backing.
He said: "The crowd were great on that last lap. I thought I was dying at that point and it (the crowd noise) was a big push behind me so that was great."
Storey sympathised with the plight of Kappes and MacLean.
"I'm really gutted," he said. "I was fighting back tears at the end. I hate to see that happen to team-mates. You really want to race the best people and they are one of the best tandems in the world."