Maria Sharapova is one of tennis’ most famous faces, but it’s the changing face of her racquet that’s recently been drawing attention.

The 23-year-old Russian and racquet manufacturer Prince announced last week that they have parted company, ending a 10-year relationship. Prince retains the right to sell a Sharapova signature line through 2011, but she will start the season with a new stick.

The announcement raises a major question: What racquet will Sharapova play with when the year’s first major, the Australian Open, begins on January 17?

Racquet customizers, stringers and devoted gear-heads speculate Sharapova has played with a blacked-out Head Radical frame for several months, making Head the likely suitor. Like diamond-cutters scrutinizing a stone for clarity, racquet techs point to photos of the all-black frame Sharapova used as proof she was not playing tournaments with a Prince, whose EXO3 technology is distinctive by the large ports on the side of the frame.

Sharapova’s representatives say there is no deal in place.

Max Eisenbud, Sharapova’s agent at IMG, told TENNIS.com he has “no comment” on the racquet his client will use in 2011. Head execs were similarly tight-lipped on the topic.

That shared silence—and the sight of the blacked-out frame Sharapova used for the final six months of the season—speaks volumes. Sharapova also shot promotional photos for the Australian Open with the same stencil-less frame, played with it in an exhibition against Vera Zvonareva earlier this month in Monterrey, Mexico, and wields it in this commercial for Google Search by Voice:

The three-time Grand Slam champion opened the season playing with a Prince EXO3 Black frame and appeared to be using that racquet when she won her 21st career title in Memphis in February. Shortly afterward at Indian Wells, she suffered a right elbow injury that would sideline her for nearly two months. When she returned to the tour in Madrid in May, she was playing with an all-black frame devoid of the Prince stencil and lacking the patented EXO3 holes. It is believed Sharapova, who has undergone a couple of shoulder surgeries in recent years, made the switch to Head in Madrid.

“The Radical is a great stick and it is believed she’s already been using that blacked-out Radical for months,” says Bruce Levine, TENNIS’ racquet adviser. “I think it’s a little thinner beam, a little more flexible and not as head-heavy as the Prince she had been using. Maria had great success playing with Prince. But when you look at the fact she’s had shoulder surgeries, and you’re using a rigid frame and a rigid string in that frame, then sometimes something’s got to give and sometimes the thing that’s going to give is your arm.”

Why Head? For one, it takes time for players to adjust to a new frame—James Blake, for example, switched from Dunlop to Prince a few years back and never felt fully comfortable, ultimately changing back—and Sharapova has already played with one for at least the last half of the year, making for a smoother transition.

There’s also the issue of dollars. Head’s top women endorsers are two-time Grand Slam champion Svetlana Kuznetsova and Victoria Azarenka—both talented players, but neither can match Sharapova’s marketing muscle. Sharapova’s earning power (she remains the highest-paid female athlete in the world, collecting $24.5 million last year, according to Forbes) places her beyond the budget of some smaller racquet companies. Still, physical cost, rather than pure compensation, could be the driving force in her decision.

“At this stage of Maria’s career, I don’t think it’s a dollars and sense issue,” Levine says. “I think it’s about finding a comfort level. She’s a flat-ball hitter who has had shoulder and elbow problems in recent years and now maybe she wants a flexible frame that is not going to give her any pain and allow her to play her game without paying that physical price.”

Sharapova is not the only star preparing to start the new year with a new frame in hand. A current top 10 player will debut a new racquet Down Under, while a few other notable names are planning to change models within their current brands.

Meanwhile, Prince is already looking ahead to the future without its most well-known player. The ITF 2010 year-end junior World No. 1 players—Russia’s Daria Gavrilova, who won the U.S. Open junior girls title, and 18-year-old Colombian Juan Sebastian Gomez—are both playing with Prince.