Before she walked on the court this morning, Carling Bassett had that feeling in her stomach again. "Sick, nervous," she calls it, and when she felt her stomach twisting into a painful knot, she knew she was ready to play tennis.

"A month ago when I went out to play, I didn't have that feeling," she said. "I just went out and played. Today, I felt sick and nervous. That was good."

And so, playing in a tournament that no one expected her to attend, Bassett won a difficult opening French Open match, defeating France's Catherine Tanvier, 7-5, 6-3. Bassett is the No. 13 seed, Tanvier is ranked 54th in the world. But playing on the red clay of Roland Garros before the partisan French fans, Bassett's victory would have been a good one under the best of circumstances.

Considering what has gone on in her life recently, it was remarkable.

Twelve days ago, her father, John F. Bassett, a wealthy Canadian businessman who once owned the Tampa Bay Bandits of the U.S. Football League, died after a long, painful fight against cancer. For his family, it marked the end of one nightmare. And the beginning of another. "No one expected me to play here," Bassett said today. "But after it happened, I knew I would play."

Bassett knew she would play, because tennis is her escape. "When I wanted to occupy my time and my mind, I started playing a lot more tennis and practicing a lot more," Bassett said today. "I ran stairs and worked a lot to keep my mind off things. I started to enjoy doing that again. I became competitive with myself. I started saying, 'Come on, do one more.'

"I'm hoping that my game and my competitive instincts will come back. I know they won't all at once. It takes time."

Because she is blond and 18 and grew up in a wealthy family, there has been a tendency to think of Bassett as another one of tennis' spoiled valley girls.

But Bassett is a tough competitor, someone who has earned the respect of the other women, especially in the last year. They have watched her deal with the pain of her father's illness, and, even with her mind clearly not on the game, maintain a top 20 ranking.

Today, Bassett's grit was very much in evidence. Tanvier is tall (5 feet 9) and very capable, especially here on the slow clay where her topspin ground strokes can drive an impatient player to distraction. Bassett began tentatively, losing her serve in the first game and trailed, 5-4, with Tanvier serving for the first set.

But at 30-all, Bassett knocked off a strong backhand down the line to get to break point, then Tanvier, making a rare foray to the net, netted a backhand volley. That made it 5-5.

"I think that was the turning point psychologically," Tanvier said. "After that, she seemed to get much stronger. She kept me back a lot and I had to be cautious. She was just better when she had to be."

Bassett was steadier than Tanvier. Neither wanted to have much to do with the net -- Bassett made errors the first five times she came in -- and for a while it appeared Tanvier's moonballing topspin might be more than Bassett could handle. But she stuck out the 60-minute first set, getting to set point with her first winning volley and then watched Tanvier push a forehand deep.

The only nervous moment of the second set for Bassett came after Tanvier had broken back to trail, 3-2, and served for 3-all. Three times, Tanvier saved break points before Bassett cracked a backhand for a clean winner. It was only a matter of time after that.

"I wanted to play here, I want to be busy," Bassett said. "I want to play a lot this summer. It was hard to leave my family to come over here but this was the best thing."

John Bassett was diagnosed as having two cancerous brain tumors in February 1985. Last October, his doctors told Bassett they thought he was cured.

But in February, Bassett started having back pains. He checked into Toronto General Hospital. The cancer had not been cured. Bassett never left the hospital.

"It's been a long time, probably since Delray Beach [February 1985] when I played with a clear mind," she said today. "You think to yourself that it doesn't affect you, but it's there. It's always there. I don't think I'll ever have a totally clear mind when I'm playing, at least not for a long time.

"But I want to go full force and play. I know a lot of people thought I would lay off after the tragedy happened. I suppose I could see myself doing that, but this is what my dad would want me to do."

The only upset of the opening day of play was a mild one. Camille Benjamin beat No. 11 seed Kathy Jordan, 1-6, 6-2, 6-3. Although Benjamin is ranked 69th in the world, she likes these courts. In 1984, she was a surprise semifinalist. Today, she controlled the last two sets against Jordan, who much prefers a fast surface.

Other seeds advanced without incident: Chris Evert Lloyd (No. 2) dominated French junior Cecile Calmette, 6-0, 6-1. Steffi Graf (No. 3), Helena Sukova (6), Gabriela Sabatini (9) and Catarina Lindqvist (12) also advanced easily.

Among the men, Ivan Lendl (1), Boris Becker (3), Stefan Edberg (5), Guillermo Vilas (12) and Johan Kriek (13) won, only Edberg dropping a set.

For Kriek, a fast-court player who has not played here in seven years, his 6-1, 7-6 (7-2), 6-2 victory over Carlos Kirmayr was his first in the French Open. Still, the South African expatriate is the highest seeded American. "I'm the highest seeded American?" he said in a shocked tone. "Geez, you're kidding me. Don't tell me, that will put pressure on me.

"I'm not over here taking things one day at a time, I'm taking them one hour at a time."

Jimmy Arias, the No. 15 seed, who sprained his right ankle Sunday in an exhibition, said the ankle felt better today and he will try to play his first-round match Tuesday against Francisco Maciel of Mexico.