Looking back, it seems perfectly understandable that it took Serena Williams some time to settle her nerves in her first singles match in nearly four years. Rennae Stubbs, one of Williams' coaches, pin-pointed a moment about an hour into the 44-year-old's defeat to an opponent less than half her age earlier this week at Wimbledon. “I noticed in the middle of the second set her take a big sort of deep breath and I actually turned around to Venus and said, ‘Oh I think she just relaxed,’” Stubbs