Even before Serena’s remarkable late-career surge, she was regarded as one of the best female tennis players ever to play. In the past year, however, she has transcended her sport and staked a claim as arguably the greatest American athlete of her era. Measuring dominance across different sports is an inexact science—how do you compare, for instance, a LeBron James to a Tiger Woods to a Serena Williams? But neither LeBron nor Tiger has yet matched Williams’ combination of dominance and longevity.

As she overcame some early jitters and dispatched Muguruza on Saturday, it became clear that Serena has not lost an ounce of poise, strength, agility, or skill despite her relatively advanced age. We aren’t just watching the greatest women’s tennis player of all time. We’re watching one whose greatest accomplishments, improbably, may be yet to come.