Serena Williams' comeback to tennis might be over before it started.

Tennis legend Serena Williams made a triumphant return to the courts on Tuesday, with a big assist from Canadian rising star Victoria Mboko.

Williams started her comeback predictably: by winning a doubles match with her first-time partner, the 19-year-old Canadian phenom Victoria Mboko, 7-6 (7-2), 6-2, beating third seeds Erin Routliffe an...