By all accounts, Christophe Roger-Vasselin should not have even been on Roland Garros Stadium's center court today against top-seeded Jimmy Connors in the quarterfinals of the French Open tennis championships.

The 25-year-old Frenchman is ranked 130th on the tour, lost in the first round in his first five tournaments this year, has never won a professional event. Even his hometown crowd mistook part of his last name for his surname, cheering him on with yells of "Allez Roger!"

But Roger-Vaselin played steady, if unspectacular, tennis, to stun Connors in three sets, 6-4, 6-4, 7-6 (7-5), and become the first Frenchman to reach the semifinals here since 1974. Later in the day, he was joined in the semifinals by Yannick Noah, who struggled with his suspect confidence before overcoming a comeback by tough Ivan Lendl, 7-5, 6-2, 5-7, 6-0.

While the two quarterfinals involving Frenchmen captured the crowd's interest, perhaps the best tennis of the day was displayed by Chris Evert Lloyd and Hana Mandlikova, also meeting to determine a semifinal berth.

Mandlikova showed some wonderful natural talent, hitting perfect drop shots and blazing base-line winners. But she often followed a brilliant shot with an unforced error. These mistakes let the steady, patient Evert finally beat her, 4-6, 6-3, 6-2.

"I gutsed it out," Evert said afterwards. "I have played better before, but I just kept plugging away to find my form. I won because I played each point with more thought than her."

In another, less exciting quarterfinal, third-seeded Andrea Jaeger easily beat amateur Gretchen Rush, 6-2, 6-2. Evert now faces Jaeger in a semifinal match Wednesday. The winner will be the overwhelming favorite to capture the championship.

This is because upsets of Martina Navratilova and Tracy Austin on the other side of the draw have produced a relatively weak pairing. A British girl, Jo Durie, victor over Austin, is pitted against the veteran Mimi Jausovec.

Even if they did not provide the best tennis, the two matches involving Frenchmen brought a standing room crowd of about 16,500 at the center court to its feet. French players have not dominated their own championship since the era of the so-called Four Musketeers, Rene Lacoste, Henri Cochet, Jaques Brugnon and Jean Borotra. One of them won the tournament every year between 1922 and 1932.

Now the French are assured of their first finalist in 37 years, and they figure they have another potential champion in Yannick Noah. The big question mark about 23-year-old Noah has always been his concentration and will to win.

Against Lendl yesterdary, Noah proved he has made progress in these two critical areas.

After sweeping through the first two sets, Noah was up, 5-2, but Lendl fought off three match point to win the next game. Noah's game proceeded to fall apart, and he lost the next five games and the set.

"I nearly died at that point, I was so nervous," Noah said. "I saw myself losing another match after having match point, in the dressing room, all depressed."

But he pulled himself together and began the fourth set agressively. A series of approach shots and lobs left Lendl off balance, and quickly Noah had swept the set, 6-0.

"When I attacked in the first game of the fourth set, I saw I had him off balance," Noah said. "I regained my confidence."

If Noah's ability to regain his confidence was somewhat surprising, Roger-Vasselin's success against Connors was absolutely sparkling. In their only meeting two years ago, also here at Roland Garros, Connors easily overcame the Frenchman in a first round match.

This time around, Roger-Vasselin decided that his only chance was to abandon his traditionally agressive game, and play steadily from the base line to Connors' weak forehand. His hope was that Connors would become impatient with Roland Arros' slow, red clay and commit unforced errors.

The strategy worked to perfection. While the rangy, handsome Frenchman sliced back returns from the base line, the pugnacious American slapped the ball all over the stadium.

"I don't know what happened," Connors said afterward, "I hit some shots so long I couldn't believe it."

But after the first two sets of colorless, erratic shot-making, Connors finally seemed to warm up to Roger-Vasselin's softball approach. His strokes became steadier and he attacked the net more aggressively.

Soon, he was up, 4-2, seemingly on his way to a semifinal berth and his best chance ever to win his ever French championship. At this point though, Roger-Vasselin gritted his teeth and struggled back.

"In the third set I began to dream a bit," Roger-Vasselin said.

"I was ready to let the set go, but then I got some breaks and my concentration returned."