Jimmy Connors romped and Vitas Gerulaitis struggled into the semifinals of the French Open tennis championships today.

However, it was a controversial default awarded to Guillermo Vilas over Manuel Orantes that created the greatest drama at Stade Roland Garros and briefly threatened to disrupt the world's premier clay court tournament.

Connors recorded a 6-4, 6-0, 6-0 routover Chilean Hans Gildmeister, who but all gave up after blowing a 4-3, 40-0 lead in the first set, winning only 28 points thereafter.

Gerulaitis toiled for 3 hours 39 minutes on the sun-baked center court before subduing Wojtek Fibak, 6-3, 5-7, 6-4, 3-6, 6-3, in a match made even more fascinating by an undercurrent of longstanding bad blood between the players.

Defending champion Chris Evert Lloyd outsteadied the usually agressive Kathy Jordan, 6-2, 6-0, and Hana Mandlikova of Czechoslovakia clobbered Argentinian Ivanna Madruga, 6-2, 6-3 to move into the women's singles semifinals.

The big news of the day, however, was the reaction of players and officials to the default of Orantes. He refused to play his fourth-round match against 1977 champion Vilas because, according to the rules, Vilas should have been defaulted Monday.

There was speculation that the Association of Tennis Professionals, the men players' guild, might boycott the tournament on behalf of lodge brother Orantes, but ATP Executive Director Butch Buchholz announced that his group would instead seek to have the tournament fined a substantial sum for its alleged breach of the rules of pro tennis.

Harold Solomon, who is scheduled to play Vilas in the quarterfinals Wednesday, dispelled rumors that he would refuse to play. Fears of a wildcat strike of players apparently vanished.

Buchholz said that the ATP would appeal to the Men's International Professional Tennis Council, which governs Grand Prix tournaments, to punish the French Open for Violating Grand Prix rules. There is an irony here, because the chairman of the council is Philippe Chatrier, president of the French and International Tennis Federations, and the man who made the controversial decision on behalf of the tournament committee that he chairs.

Vilas and Orantes were scheduled to play Monday, but Vilas appealed for a delay because of an intestinal problem. The tournament doctor said Vilas would be able to play within 45 to 60 minutes after treatment and Chatrier authorized this delay.

Orantes said he was never informed, and was on the court to play the match at the scheduled time. According to Grand Prix rules, a player who is more than 15 minutes tardy is disqualified.

The four globe-trotting Grand Prix supervisors employed by the men's pro council to enforce the rules all agreed that Vilas should be defaulted, but Chatrier and his tournament committee disagreed. They blamed a breakdown in communication and rescheduled the match for today.

Orantes, claiming that unfair preferential treatment was being given Vilas, refused to play and was defaulted by the tournament referee.

Orantes and Buchholz insisted at a press conference that the rules had been violated and the authority of the Grand Prix supervisors undermined Chatrier argued that the tournament committee had the prerogative of granting Vilas a delay for medical reason, and that the supervisors have authority over a match only once it is on court.

Chatrier took full responsibility for the tournament decision. But he said, "sport is the loser."

Orantes disagreed: "I have been injured and sick before, all players have been, and you are not given time to recover.

"This is just bad luck; you play or default," he said. "We live in a professional world, and the rules must be the same for everyone. The tournament should not favor one player over another. If the rules are enforced the same for everybody, then sport is the winner,"

After a full day of meetings and sometimes heated rhetoric from players and officials, it appeared that the tournament would not be further disrupted, but that the matter would be adjudicated by the men's pro council at its meeting in London, June 17-19.

Of the matches that were played today, Gerulaitis' victory over Fibak was by far the best. It came down to a single servicebreak in the fifth set.

"I guess we just play the same way. We both like to attack, we both try to get to the net on the other's backhand. I guess that's why we are playing always such close matches." said Fibak, who hasn't spoken to Gerulaitis in a year, since he refused to shake hands after Fibrak won a match at Forest Hills, N.Y.

There was a current of tension and psychological warfare throughout the match, which was characterized by attacking, full-court points.

Afterwards, Fibak said he would like to bury the hatchet with Gerulaitis, whom he has called a bad sport. Gerulaitis said he had no desire to make friends with Fibrak. He refused to elaborate on their feud, but in the past has called Fibak a gamesman and cheat.

"There's no guy I would rather beat," said Gerulaitis, who plays Connors -- whose form has steadily improved throughout the tournament -- in Friday's semifinals. "There was no way "I was going to let Fibrak get through to the semis."