SAITAMA, Japan — Nathan Chen, the defending champion, produced a spectacular free skate on Saturday to win the gold medal at the World Figure Skating Championships.

Chen, 19, who was first after the short program, made no mistakes and landed four quadruple jumps to finish with 323.42 points.

Chen, a freshman at Yale, opened with a quad Lutz and followed with a quad flip. The United States national champion, he then added two quad toe loops, one in combination, to solidify his lead.

“I’m proud of myself for being able to put out two good programs, the short and the long,” Chen said. “Ultimately, I’m just happy with how this event went, and I hope to have more experiences like this.”