Serena Williams Boyfriend 2013: Patrick Mouratoglou Gives Girlfriend Track Top? American Tennis Star Posts Twitter Photo Allegedly Wearing Boyfriend’s Clothing

Serena Williams posted a photo of herself on Twitter holding her dog Chip in what appears to be a gym facility, but the track top she was wearing might have been given to her by coach and rumored boyfriend Patrick Mouratoglou, giving more evidence of their possible relationship.

"Nice outfit," wrote on fan in the photo's comments section. "lool you're wearing Patrick's top haha."

Last week, the American tennis star posted several messages on Twitter about her "boring vacation" and her time away from the tennis court as her coach and rumored boyfriend Patrick Mouratoglou has her resting after her recent victory in Istanbul.

"Only one day off and I'm already getting bored. I really should have planned a real vacy...." she posted on Twitter.

"Well I just bought Sidney Sheldon book so it will be a page turner. It's called 'Master of the game' here I go..."

Serena Williams also made headlines for a statement her coach and rumored boyfriend Patrick Mouratoglou made about her rising performance and fame.

Patrick Mouratoglou told the New York Times in a recent interview that she "still has a margin for improvement that is enormous," giving insight into his longtime commitment to her career.

The French tennis legend also mentioned that Serena Williams is one of the best tennis players he has coached.

"Serena will never drop her guard. She will stop perhaps, but she won't drop her guard. She won't be 50th in the world, that's for sure. She wouldn't accept it from herself. It's not the style of the maison," he told the New York Times.

"It can't hurt, that's for sure. For sure it helps. She told me all the trophies we win when we work together we'll put them in the academy. They are in the entry. We reorganized. We made a big room like a players' lounge in the entry with the bar and put a trophy case there, which is already full."