World No 1 and 17-time Grand Slam Champion Serena Williams celebrates her 32nd birthday on Thursday. She has a lot to be thankful for.

She is deemed as one of the greatest tennis players of all time. She currently holds the record for the most wins in singles, doubles and mixed doubles among other male or female players. She is the only player to have achieved a Career Golden Slam in both the singles and doubles divisions. She has won four Olympic gold medals and she is the only tennis player to have received more than $50 million prize money. The list goes on. What more could she really ask for? Perhaps, a loving relationship with the person she loves the most? Why not?

Serena Williams is rumoured to have a relationship with her coach Patrick Mouratoglou. She neither confirms nor denies it.

She made a statement after the French Open about her relationship with her coach. "Patrick and I have a great communication," she stated. "It is absolutely a two-way communication, he's open to me and I am open to him and I believe, it creates something special," she added.

Then she released another statement after the U.S. Open. "You just do not mix pleasure with business, I firmly believe in not mixing pleasure with business," Williams said.

It is hard to tell what the status of her relationship with Mouratoglou really is. Serena Williams seemed to have found a way to make his coach green-eyed and jealous with her new friend in Dan Ogee, a hockey player. The two, apparently, exchanged flirty conversations on Twitter. Check out the snippets we found on popular social networking site below.

What do you think Mouratoglou will say about this? The French coach often posts pictures of Serena and him on his Facebook account and brags about her achievements. Maybe it is his way of showing the public that that Serena and him are just beginning to be more open about their relationship.