American teenager Regan Smith smashed the women's 200 metres backstroke world record Friday, lopping a huge chunk off countrywoman Missy Franklin's old mark.

USA's Regan Smith competes in a heat for the women's 200m backstroke event during the swimming competition at the 2019 World Championships at Nambu University Municipal Aquatics Center in Gwangju, South Korea, on July 26, 2019. (Photo: VCG)

The 17-year-old stormed to victory in the second semi-final in Gwangju, firing off a time of two minutes, 3.35 seconds -- a whopping 0.71 faster than Franklin swam at the 2012 London Olympics.