Defending champion Adriano Panatta, troubled by a tricky breeze and by 21-year-old Englishman Buster Mottram, labored for just under three hours and finally escaped safely to the quarterfinals, 2-6, 4-6, 6-3, 6-4, 6-4, today in the French Open tennis championships.

Wojtek Fibak of Poland also suffered some anxieties, and squandered more leads than he would care to remember, before beating young Rolf Gehring of West Germany, 6-7, 6-4, 6-2, 3-6, 6-4.

Raul Ramirez and Guillermo Vilas, who have each lost only one set in four matches, advanced to the last eight in routs.

The case of Ramirez' victory, 6-2, 6-4, 6-3, over South African John Yuill, was not unexpected. The simplicity with which Vilas Brushed aside Stan Smith was 6-1, 6-2, 6-1, in barely more than an hour.

Smith's rapid exit in a torrent of lefthanded topspin, effective as a clay-colored tornado, left Brian Gottfried as the last of the Americans in the men's singles. He has not lost a set yet and should have a good chance to beat top-seeded Ilie Nastase, the champion of 1973, in their quarterfinal meeting Wednesday.

Mima Jausovec, seeded No. 1 in a women's singles event depleted by World Team Service Tennis, moved into the semifinals by defeating Pam Teeguarden, 7-5, 6-4. Regina Marsikova joined her by winning an agonizing battle over fellow Czech Renta Tomanova, runner-up here last year, 7-6, 6-7, 6-3.

Panatta, the swashbuckling No. 1 player of Italy who last year won the Italian and French open titles back-to-back, played for the first 70 minutes like a man trying to prevent his crown from being blown off like the linesmen's hats. Thereafter he got down to business - which for him means attacking tennis - and played the agressive shots that earned him titiles to defend.

Mottram broke in the first game of the first two sets, which did not do wonders for Panatta's self-esteem, and broke again for 5-2 in each. Panatta, his forehand awry, backhand misfiring, and normally punishing severe eratic, did not have a break point will the eighth game of the second set and at one stage lost 19 to 22 points.

Panatta's service tons seemed affected by changing air currents, but curiously is lobbing was not. That was the one consistently effective aspect of his game. Time and again he floated the ball in perfect arcs over the 6-foot-3 mottram, who could only turn and watch forlornly as the winners dug pock makrs along the baseline.

As the shadows lengthened on the center court, bathe in sunlight but chilled by the sunlight that chilled by the brezze, Panatta decided at two sets to love down to throw caution to the wind.

He got some advice from a fellow Italian during the interval between the third and fourth sets, and heeded it.

He Started attacking at every opportunity instead of fiddling with Mottram, who had played steadily and thougfully the first two sets, pushing the ball back, tormenting the sturday, 6-foot-2 Panatta with nothing balls.

He stopped hitting to the backhand corner, from which Mottram has a very good down-the-line passing shot when he has the room to take a full, flowing swing. Mottram is less effective where cramped, and Panatta started hitting deep and into his body.

He eerved more down the middle cutting down the angles Mottram and feasted on.

He worried less about his inconsistent first serve and concentrated on getting his second delivery deep, with something on it, taking away Mottram's earlier options of either hitting out on his returns or chipping them and coming in to the net.

Panatta lost his earlier inhibitions and Mottram began to counterattack, I11-advisedly because he does not put many volleys away and has a weak overhead.

Panaatta broke at love for 3-2 in the fifth set when Mottram netted a smash after two volleys that he studpidly hit right at Panatta, even though he had lots of open courts to aim for.

Panatta broke again for 5-2, Mottram hitting another terrible smash long but had to serve for the match twice as Mottram Grittily broke back to 3-5 and held for 4-5.

Panatta was down 0-30 in the final game, reverting briefly to his earlier tentativeness, but won the last four points. He ended the match in a manner that rekindled memories of his victory last year, Putting away a decisive forehand cross-court volley and pulverizing an overhead. Children rushed on the court, surrounded Panatta, and tried to grab his wrist bands as souvenirs.

Fibak was broken when he served for the match at 5-3 in the fifth set against Gehring, who took him to five sets in the first round here last year. Gehring, 22, was a "lucky loser" who filled the vacancy left when Manuel Orantes flew to Washington for surgery on his ailing left arm. He got to the fourth round by beating Caech Pavel Hutka, the man he lost to in the final round of qualifying.

Gehring, who has a reputation for folding at the end of good matches, broke back for 5-4, but lost his serve for the match, netting a backhand volley off a backhand cross-court return. That feeble ending seemed somehow appropriate to a match neither player seemed anxious to grasp.

Vilas simply ran circles around Smith, who did not play as badly as the socres might indicate until the match was already sliding out of reach.

Vilas grew up with slow clay between his toes. Smith did not. Today it showed.

Vilas, sprinting and sliding surely around the court, whacked his ground strokes hard and deep, and mixed in some soft stuff and angles when it behooved him to do so. Smith tried to get to the net and was passed as regularly as a bicyclist on a superhighway.

It was no contest. Viles looked strong and totally in control. Smith looked strong and totally at sea. The 6-foot-4 American was reduced to shaking his head and trying not to look embarrassed as Vilas cracked backhand returns and passing shots that exploded like firecrackers.

Vilas, who has been called "the young bull of the pampas," crunched his volleys, his overheads, his ground strokes. He only worked up a sweat because he wanted to. The better he played, the more Smith crumbled.