Thousands of kids and their families from across the tristate area helped kick off the U.S. Open on Saturday, celebrating sports legend Arthur Ashe's mantra that world-class tennis be made accessible to all races and ethnicities, rich or poor.

For 20 years, Arthur Ashe Kids' Day has used the tennis arena in Flushing Meadows to offer free tennis lessons to children and volley time with professional players.

"It's amazing how much tennis has grown and how this great event has brought the tennis community together," said Patrick McEnroe, U.S. Open tennis analyst and brother of tennis icon John McEnroe, who first competed in the U.S. Open in 1977.

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"It was always Arthur Ashe's vision that everybody, including the kids from the inner city, should have a chance to play," said Patrick McEnroe, who hit balls with the children and with his 9-year-old daughter.

"I love the fact that she loves to play and that she is improving, and that she is enjoying it, which is number one," he said.

Children as young as age 4 had the chance to hold a racket and hit the ball with pros such as Caroline Garcia of France and Taylor Townsend of the United States.

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While taking their best shots, the kids were videotaped by excited parents and grandparents who say they have passed on a family tradition.

"They are enjoying themselves," said Stewart Greenfield, 39, of Melville, who watched from the stands as his identical 7-year-old twin sons, Max and Harrison, warmed up for their volleys at the Billie Jean King National Tennis Center. "This is the first time we have come, and it's awesome," Greenfield said. "It's a great sport, and it's something you can do your entire life."

Greenfield, who played as a child and met his wife, Kara, 39, on the courts, said the sport helps "develop patience."

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Stephen Daniels, 76, of Westport, Connecticut, watched his 4-, 6- and 9-year-old grandchildren hit balls. "My wife and I played, and we introduced it to our son, whose children are here today," he said.

Daniels said he loves tennis because "it's competitive and it's not a violent sport that can cause injuries."

It requires "practice and patience," he said. "It is my hope that my grandchildren will enjoy it enough so that they too can play as long as we have. It's a family sport."

Aaron Dozsa, 10, of Rego Park, Queens, started playing at age 4. "I like it because it helps me run faster. It's just fun to use a racket to hit a ball."

His father, Victor, 47, said tennis "is a good way to develop individualism, and it is athletically challenging."

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Money raised from the $10 tickets will benefit the United States Tennis Association Foundation, which helps fund the National Junior Tennis and Learning Network. The network provides free and inexpensive tennis lessons to more than 225,000 children each year.