The U.S. Open is an annual parade of sporty styles with players wearing new athletic apparel that will hit retail stores in a hurry. The major brands have staked out their sponsorships, but no label has done so more than Polo Ralph Lauren. The American mega-brand has entered into a partnership with the United States Tennis Association that will make Polo Ralph Lauren the official apparel sponsor of the Open for the next four years.

Signs of the partnership won’t be hard to miss. Line judges and ball persons will be wearing shirts and pants or skirts designed by the label. A 3,500-square-foot retail space will be located on the grounds of Flushing Meadows Park. The official U.S. Open Polo shirt comes complete with an enlarged version of the famous polo-player logo that now measures 5 inches. The logo will also appear prominently at courtside and on the video and electronic boards that instruct viewers where to watch their favorite players.

Like most contemporary manufacturers of sports apparel, Polo Ralph Lauren is using a high-performance mesh fabric – designed to dry quickly – in its garments, including those for the line officials. An “airflow jersey” will be used on additional shirts in the high-performance collection.

Co-branded merchandise will include tote bags, tennis dresses, skirts, sweaters, caps, and more shirts. But there will also be some merchandise that benefits a cause. Polo Ralph Lauren has created a line of white tennis balls sporting the polo-player logo in pink. All profits from the sales of the balls will go to the Pink Pony Fund, which supports cancer education, outreach, and research. The fund was initially created to focus on breast cancer, and the color pink was chosen as a visual reminder of that cause.

Though Ralph Lauren will dominate this year (and the next three), the event’s competitors will be wearing a variety of athletic brands. The new no. 1 seed on the women’s side, Maria Sharapova, will be wearing Nike’s light blue tennis dress trimmed in yellow, which is already available for purchase. Reebok is sponsoring Nicole Vaidisova, who will be wearing a pink tennis dress she helped design. According to a spokesman for Reebok, the designers tapped runway trends – a high neck and lots of mesh – to create a look that straddles fashion and performance.

Last year’s champion, Svetlana Kuznetsova, is sponsored by Fila, as is Kim Clijsters. They’ll both be wearing clothing from Fila’s Tournament Collection, available to consumers at the new Fila flagship store at 340 Madison Avenue.

Patti Gallagher, Fila’s global product manager for tennis for apparel, created the 2005 look by sitting down and talking with the players. “I meet with them and talk to them about what their needs are and what they are interested in fabric-wise,” Ms. Gallagher said. “We get their input because they’re playing with it on a regular basis.”

Fila is also sponsoring several members of the men’s tour, including Mark Philippoussis. The color scheme for both men and women will be red, navy, and white. “You will see a correlation between the men’s and women apparel,” said Ms. Gallagher. “The women’s is a little more feminine. The men’s cotton is a tactile pique – soft but with a performance element.”

No matter what the players are wearing, the scene in the stands at the U.S. Open will be a mix of sporty and stylish. No degree of heat is going to keep this crowd from looking its best. Come dressed to stay cool – and hot.