An emotional Non Stanford felt she had let her home city down after struggling with fitness during the World Series Triathlon event in Leeds.
Stanford had fought a virus in the lead-up to the race and found herself off the pace in all three disciplines as she finished 11th.
The 28-year-old trailed by almost a minute after the swim and was unable to surmount the gap despite the assistance of fellow Yorkshire racer Jess Learmonth, who finished in a career-best sixth place.
“It was a struggle from start to finish,” Stanford said. “It was a team delivery race and I didn’t deliver, which is the toughest thing when you have had people sacrifice their race for you can’t deliver.
“The crowds got me round today. If it wasn’t for them I wouldn’t have made that finish line. I wanted to give themselves something to cheer and felt I’d let them down today.”
Duffy was in the leading groups in the swim and cycle before surging clear in the early stages of the run to back up her victory in Yokohama.
The 29-year-old stopped the clock on the blue-carpeted finish line at Millenium Square in one hour, 57 minutes two seconds, ahead of American Taylor Spivey and Italian Alice Betto.
Stanford’s chances of winning all but disappeared during the swim in Roundhay Park where Learmonth created a fierce pace at the front.
Learmonth, who started triathlon only five years ago, left the water six seconds ahead of Duffy in 17.47 but Stanford found herself in a third group 50 seconds further behind.
As part of team tactics, Learmonth dropped back to join Stanford but they lost more ground in the cycle leg and the latter produced the quicker run to earn a career-best finish.
“It’s unbelievable,” Learmonth said. “Leeds last year was my best finish and now this, two better. I hope I can do that better. I am happy to do team tactics that we knew from the start. I never come out thinking I wish this or that had happened. In triathlon anything can happen.
“I’m just happy to make that progression. Progression needs to be quick and hopefully it continues.”