Serena Williams in Sydney. (Courtesy of Wikimedia Commons)

In this look back at tennis history, let's wind it back to 1997 – and the occasion of Serena Williams' first-ever match in a major tournament. Consider this splendid 21-shot rally in the first round of US Open women's doubles:

Now consider further: One of her two opponents on that day was Kathy Rinaldi, who is now, at age 51, the U.S. Fed Cup team's captain. That's just mind-boggling, and another stark reminder of the Serena's staying power in the sport.

By the by, despite grabbing the glory in that lengthy point – chock-full of groundstroke and volley prowess – the team of Rinaldi and partner Jill Hetherington actually defeated the Williams sisters by a 6-4, 7-5 score. Still, who knew what dreams would come?

Follow Jon on Twitter: @jonscott9.