Serena Williams of the U.S.celebrates defeating compatriot Taylor Townsend during their women's singles match at the U.S. Open tennis tournament in New York August 26, 2014. REUTERS/Shannon Stapleton
#6 Serena Williams Total earnings: $22 million Prize money: $11 million Endorsements: $11 million REUTERS

Being a fashion maven and a big server, world no. 1 Serena Williams loves the protective sleeve that Milos Raonic wears on his right arm during matches.

The 17-time Grand Slam champion went so far to inquire on Twitter about the sleeve that the hard-serving Canadian wears. While on a day off from the U.S. Open, Williams asked Raonic if the sleeve he is wearing would improve her serve.

Serena Williams is a fan of Milos Raonic. Specifically, she loves the protective sleeve that the hard-serving Canadian wears on his right arm.

"@serenawilliams: @milosraonic I love your arm sleeve. It's super cool. Will it help my serve? #CanIHaveOne" Yes! #BelieveInTheSleeve

— Milos Raonic (@milosraonic) September 1, 2014

What began as a health need has turned into a superstition for the Canadian Raonic and the American tennis superstar thinks it looks stylish.

Not that the 33-year-old needs help with serve as she leads the WTA in aces just recently.

Raonic started wearing the sleeve last March to protect a rash from exposure to sunlight and he is now on the third in aces on the men's tour. The Canadian had only started wearing bright and solid colours in the past, white most of the time, grey and clue in Cincinnati.

Last Saturday, Raonic wore one with a bold pattern that caught the eye of Williams and other WTA players.

Lol oopssie!!! I think everyone is ready for it! RT"@vika7: @serenawilliams @milosraonic get in line lol"

— Serena Williams (@serenawilliams) September 1, 2014

"I'm not going to argue when things are going OK". Raonic answered when asked if he thinks his arm sleeve helps his serve.

Meanwhile, Serena Williams is already the lone American tennis player in singles at the U.S. Open that makes her a step closer to her third consecutive U.S. Open title.