As the tennis world prepares to welcome Serena Williams back to doubles competition, the 39-time Grand Slam champion overall is not ruling out a return to the singles bracket.  “I can’t say no right now,” she told reporters after a training session with her Queen’s Club doubles partner, Victoria Mboko, on Sunday. “I feel like I probably need to train a little bit more if I want to play singles, and we will see if I get there, and if not … that’s not my journey right now.” Williams was granted a