Decades ago, when the Williams sisters were children in California, taking tennis lessons from their dad on a municipal court and imagining playing at Grand Slam tournaments one day, it was Venus - older, taller, stronger - who usually beat Serena.

Never a fan of losing to her sibling - who would be? - Serena cheated a tad every so often, lying about whether Venus' shots landed in or out.

"That's the past," Serena jokes now with an eye roll. "I was young."