Laura Trott, Katie Archibald, Elinor Barker and Joanna Rowsell were quickest in qualifying by two seconds but were pushed hard by Canada in the final.
Since the event changed to four kilometres and four riders, Olympic champions Great Britain have been hard to beat over the distance.
But Canada gave them their toughest test yet, finishing just over a second behind after they decisively lost a rider.
However, Barker also lost a wheel in the closing stages, admitting she found the pace 'too fast'.
"A perfect ride is always nice but a stripey jersey is a stripey jersey so I guess that's all that matters," double Olympic champion Trott told britishcycling.org.uk.
"I'm not sure what happened to the Canadians, they ended up with three riders so they also didn't have a perfect ride so you get lucky sometimes I guess and that's what happened."
Rowsell also admitted the form of the Canadian quartet serves as a timely reminder that Great Britain cannot take their domination of the discipline for granted.
"We were riding to our schedule in the first half of the race and our coach kept telling us we were down," she said.
"We were panicking a bit, thinking it's never going to come back. It was just a race all the way to the line, everyone gave their all and I think we were all on our knees at the end there."
Elsewhere, Becky James finished fifth in the women's 500m time time trial, reigning world champion Jason Kenny settled for fifth in the men's keirin final, after clashing with Germany's Max Levy in the final lap, and Jon Dibben ranked 14th in the men's scratch race.