TOKYO — Sydney McLaughlin recently said that “iron sharpens iron” when it comes to her relationship with Dalilah Muhammad. They are the preeminent practitioners of their craft, the two fastest women ever to run the 400-meter hurdles.

Few events were more highly anticipated at the Tokyo Games than the renewal of their rivalry on Wednesday at Olympic Stadium.

It was safe to assume that something extraordinary would happen, and McLaughlin delivered, breaking her own world record to win her first Olympic gold.

McLaughlin finished in 51.46 seconds. Muhammad ran the fastest time of her life to take the silver medal in 51.58 seconds, and Femke Bol of the Netherlands was third.