Cary Stansbury of Larkspur, Calif., qualified for the Washington Star International tennis championships yesterday but not without a grueling 2 1/2-hour trouble, Stansbury gets to play Jose Higueras of Spain in the first round and may be fined $250 for wearing an improper shirt yesterday.

Stansbury defeated Roger Guedes of Brazil, 6-3, 5-7, 6-4, and said, "I haven't played too many matches this tough before."

It was the Junior Davis Cup player's first trying to qualify for the Star tournament.

Guedes, 24, had been third seeded among the potential qualifiers for the eight open spots in the 64-man field of the $175,000 tournament that gets rolling today at the Washington Tennis Stadium, 16th and Kennedy streets NW.

Stansbury won the first three games and the first set easily. In the second set, the Brazilian, a graduate of Hampton Institute in Virginia, turned the match around.

Stansbury continued to serve hard, but Guedes now was combating his serves with less and less difficulty. When the score reached 5-all in the second set the rain began. The showers were to Guedes' advantage. Guedes agreed, noting "Stansbury has a big serve and when bigger, which slowed his fast serve down."

Guedes won the first game of the deciding set. With the score at 40-30 in Guedes' favor in the second game, play was suspended.

Before play resumed Stansbury was called to the umpire's chair. He had re-entered the clay court with a green T-shirt with the leters WCT (World Championship Tennis) across his chest. Before the delay he had been wearing a green and white tennis shirt, with no lettering.

According to Harold Demoody, the deputy umpire, Colgate Grand Prix rules stipulate that T-shirts cannot be more than two square inches. Stansbury violate both rules, according to Demoody.

"Stansbury will be fined $250 for breaking the Colgate Grand Prix code of conduct," said Demoody.

Afterwards Stansbury, who went on to win the final set, said "I turned my shirt around. I don't know anything about the fine. I thought the rule was for final rounds. This is just the qualifying rounds. Why should I be fined? I'm not getting money for playing."

Although he has made it into the first round.Stansbury is not confident about advancing. "You like to say that you can win against some of these guys like (Jimmy) Connors. I feel inferior to these guys."

Connors, top seed in the tournament, makes his first appearance since losing in straight sets to Bjorn Borg in the final of Wimbledon July 8 when he meets John Marks of Australia tonight.

The Connors-Marks match follows the Dick Stockton-John Yuill 7 p.m. evening opener. John McEnroe, a rising 19-year-old star, concludes the night program against Robert Lombardi.

The day program begins at noon, with matches on five different courts.