USA's Sunisa Lee won the women's all-around gymnastics gold medal at the Tokyo Olympics on Thursday as Simone Biles cheered on from the stands at the Ariake Gymnastics Centre.Lee scored 57.433 to finish ahead of Brazil's Rebeca Andrade in second and the Russian Olympic Committee's Angelina Melnikova in third, extending a run of five all-around Olympic golds for Team USA. The 18-year-old Lee took the lead from Andrade, who becomes Brazil's first Olympic medalist in gymnastics, after the third rotation, and completed her victory when she scored 13.700 with her floor routine.Much of the build-up to the final had been dominated by Biles' withdrawal from the event to protect her mental health. Biles, a four-time Olympic gold medalist and all-around champion in Rio five years ago, had pulled out of the team competition earlier this week.Alongside teammate and close friend Jordan Chiles, Biles was there to cheer and clap for Lee and USA's Jade Carey.Video: Olympic Opening CeremonyThe gold medal adds to the silver Lee won with Team USA in the team competition on Tuesday.