Serena Williams enjoyed a little fun in the sun on Miami Beach with on-off boyfriend Common on Monday,October 4.Showing off her superbly fit frame, the tennis ace donned a skimpy bikini as she played around in the water in between time in a lounge chair next to her hip-hop star beau.The beach outing comes as Serena continues to take time off from tennis as she recovers from foot surgery after walking through glass at a restaurant in Munich.