The match was on court 18, stuck in a far corner of the U.S. Tennis Center, and by the time it ended it was dusk and most of the afternoon crowd at the U.S. Open had gone home.

But when Regina Marsikova walked off the court this evening with a 6-3, 6-2 victory over Emilse Raponi-Longo she felt as if she had won far more than just another first-round match.

Four years ago Marsikova played here as the No. 11 player in the world. But two weeks after the tournament, at home in Prague, she was involved in a fatal automobile accident. The details are sketchy and Marsikova's easy smile freezes with fear when she is asked about it, but someone in the other car died and Marsikova was found culpable in the accident.

At 22 she went from the whirlwind life of a top woman tennis player to that of a prisoner, first during a brief period of incarceration, then during a probationary period when she could play tennis initially only in Czechoslovakia and then in other Eastern Bloc nations.

"Almost every other day I was ready to give up," she said tonight. "I didn't feel like practicing or anything because it was tough to push myself. It just made no sense. I would say to myself, 'Oh, my God, why am I practicing?' I wondered if I would ever come back."

She came back to the tour in March, having been granted, according to her agent Larry Berkman, "total amnesty" by the Czech government. Her first breakthrough came at a tournament in Houston, where she played through the qualifying rounds to the quarterfinals before losing to Martina Navratilova. A week later she reached the semifinals at Barcelona. But it has been difficult.

"Every time I would get ahead I would get so nervous I almost couldn't play the match," she said. "I wanted to win so badly. It's tougher, too, because so many girls are good players now. Before when I played, the top 20 was good and that was about it. Now, anyone in the top 100 is tough."

Marsikova, 5 feet 9 and 153 pounds, is a powerful serve-and-volley player on the court, much in the mold of expatriate Czech Navratilova. Off the court, she is friendly, with a wide-open face and blue eyes that sparkle when she smiles.

Berkman, who first met Marsikova nine years ago when she stayed at his house in Houston during a tournament, kept in close touch with her while she was in prison and visited her last summer in Prague when she was free but still restricted. Another visitor was Andrea Jaeger, who also wrote, called on the phone and got other tour players to write to Marsikova.

Marsikova was ranked in the top 15 in the world for five years before the accident. She is now back up to No. 53 and at 26 says she would like to play until she is about 30. Next month she will represent Czechoslovakia in the Federation Cup, a complete return to good grace in the eyes of the government.

But the past still makes her nervous. Ask about the accident and she says, "I can't talk about it, it's behind me." Did the government make her an example? Again, a troubled look and no answer.

"You have to understand," Berkman said. "She just doesn't want to talk about it."

During her restricted period Marsikova played in small tournaments but found herself getting rusty because of a lack of competition. Last year in the only WTA tournament in the Eastern Bloc (at Sofia, Bulgaria) Marsikova won. But when she returned to the tour, the level of competition was a shock. However, she has played her way back and feels comfortable again traveling the tour.

"The other girls have been friendly and nice, encouraging," she said. "They come up and tell me they are glad I have come back."

She smiled. "I am very happy just be here and able to play tennis. I am enjoying the competition."

And, undoubtedly, her freedom.