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 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).
