Teenage American figure skater Alysa Liu claimed the women's world title in Boston to cap a remarkable return after retiring from the sport aged just 16.

The 19-year-old produced a captivating free-skate routine, to the delight of her home crowd at TD Garden, to edge out Japan's three-time defending champion Kaori Sakamoto.

Liu quit the sport after winning a bronze medal at the 2022 World Championships and only returned to competition last year.

"This is an insane story," Liu told broadcaster NBC. "I don't know how I came back to be world champion. I never would have thought."

Liu was last on the ice and had to watch as Sakamoto produced a high-quality free-skate routine of her own to move up from fifth place after the short programme to take the lead.

If she was feeling the pressure the young Californian did not show it, as she whipped up the crowd to a soundtrack of Donna Summer's "MacArthur Park" before ending with a flawless double Axel on her final jump.

Her overall score of 222.97 was enough to see Liu become the first American since Kimmie Meissner in 2006 to claim the women's world title.

She did a cartwheel on her way to collect her gold medal, with Japan's Mone Chiba joining compatriot Sakamoto on the podium after claiming bronze.

Meanwhile, Great Britain's Lilah Fear and Lewis Gibson will return to the ice in Boston later on Saturday in the pairs' ice dance competition.

They are in third place after scoring 83.86 in Friday's rhythm dance, behind American two-time defending champions Madison Chock and Evan Bates (90.18) and Canadians Piper Gilles and Paul Poirier (86.44).