“You’re only as good as your opponent makes you play,” Martina Navratilova observes in “Strokes of Genius.” It’s a documentary about Rafael Nadal’s hard-fought triumph over Roger Federer in the 2008 Wimbledon final, which Jon Wertheim describes in his book of the same name as the greatest tennis match to date….
Read MoreThe Blues Brothers: Roger Federer and Novak Djokovic bow as a doubles team at the Laver Cup. Photograph by Clive Brunskill for Getty Images North America