Ah, here is an article in featuring of the Doc:
"Unmatched" | 30 For 30 | TV Club | TV | The A.V. Club
And I'm not sure if you can watch the entire viewing online yet (or ever) but I did happen to find, and will provide, the official-unoffical site preface to the Doc:
ESPN's '30 for 30' documentary 'Unmatched' focuses on the rivalry and friendship between Martina Navratilova and Chris Evert - ESPN
It's great, yet also grating, then great all over again (it's in the way the story is told).
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+ bonus
I found this video on youtube as well, but it is like a trailer of sorts, not the entire full-length feature to which I am alluding.