A NET GAIN : Mixing doubles with a smashing service to charity.

South Bay tennis players will don their tennis togs this weekend to serve up an ace for charity.

The 28th annual Jim Pugh Peninsula Racquet Round-up, a two-day mixed doubles amateur event to benefit the Harbor Foundation for the Retarded, gets under way Saturday at 9 a.m. on some of the area’s most exclusive tennis courts.

The event, the oldest doubles tournament in Southern California according to organizers, features about 130 players who pay to enter the contest and compete on courts at private homes and at the Jack Kramer Tennis Club in Rolling Hills Estates.

Also part of the fund-raising effort are a dinner dance gala, silent auction and an exhibition match featuring Jim Pugh and three other professionals. All proceeds will benefit the Harbor Foundation, a nonprofit organization that provides educational and vocational training to about 250 adults with developmental disabilities.

The Racquet Round-up, started by local community leaders in 1965 as a way to support the center, is one of the foundation’s biggest fund-raisers. Such benefits have become increasingly important to the organization’s survival, said spokeswoman Diane Ortmann.

In the past year, the Harbor Foundation has lost eight staffers and 12% of its $2 million budget. It was also forced to close its preschool in March because of state cutbacks, Ortmann said.

“We have more clients than ever and less money,” she said.

The organization offers several programs serving adults 18 to 60. Clients are trained to live independently and to perform such jobs as packaging and assembly. About 22 Harbor Foundation clients currently hold jobs in the community, performing restaurant, recycling and janitorial services.

As part of the fund-raiser, Pugh will team up with three other guest professional players in a mixed doubles exhibition match at 2 p.m. Sunday at the Jack Kramer Tennis Club. Pugh, who has won doubles titles at Wimbledon, the Australian Open and in Davis Cup competition, is a Palos Verdes resident.

He recalls that as a youngster he was kicked off the tennis court at his home each year to make room for tournament players. In 1992, he was tapped to become the event’s honorary chairman. “I was honored that they wanted me to do it,” Pugh said. “They’ve had some of the top players in the world as honorees.”

The benefit will be one of Pugh’s last duties before leaving to play at Wimbledon later this month, and he promises a competitive match.

“Last year’s match was unbelievable,” he said. “It went to a tie-breaker. It was as close as it could be, so it was exciting for everyone.”

The exhibition should “teach us what we ought to be doing out there,” said Barry Freeman, director of tournament promotions, who has competed for eight years in the amateur matches.

The round-robin tournament begins with competition for individual court championships on 20 private courts from 9 a.m. to 3 p.m. Saturday.

Players and fans can take a break from the competition and attend the dinner dance gala and silent auction beginning at 6 p.m. Saturday at the Jack Kramer Tennis Club. The catered buffet will be followed by an auction featuring more than 60 items ranging from dinner for two to autographed Paul Conrad lithographs. Tickets to the dinner dance will cost $25 per person.

The tournament continues Sunday at 9 a.m. with semifinal matches on private courts. Finals begin at 12:30 p.m. at the Jack Kramer Tennis Club followed by the exhibition match.

The event also includes a raffle Sunday at noon for prizes such as a color television, cellular phone and round-trip tickets on United Airlines. Tickets for the drawing are $5.

Sponsors for the benefit include Texaco, South Bay Lexus and Home Savings of America. The fee to participate in the tournament is $35. The Jack Kramer Tennis Club is at 11 Monticello Drive, Rolling Hills Estates. Information: (310) 541-6304.