Defending champion Bjorn Borg, who struggled through his first two matches in the French Open tennis championships in rather listless fashion, returned to brilliant form today and lit up the center court at Stade Roland Garros on a gray, gloomy afternoon.

Borg, the champion of 1974, '75, and '78 who will celebrate his 23rd birthday next week, electrified a near capacity crow with a stream of flashing winners in the second and third sets to overwhelm Ray Moore, 32, the South African who now lives in Palm Springs, Calif., 6-3, 6-1, 6-0.

Arthur Ashe, who was seeded ninth but never has been comfortable on the slow, red clay courts of Europe, was not steady enough from the back-court to cope with Ivan Lendl, 19, an improving Czechoslovakian.

Lendl kept pounding big forehands and expanding in self-assurance as he hammered out a solid 5-7, 7-6, 6-2, 6-3 victory.

The only other seeded man beaten today was No. 16 Adriano Panatta of Italy, who played up to his title-winning form of 1976 for two sets, then suffered an acute energy shortage and fell to 20-year-old Californian Eliot Teltscher, 3-6, 3-6, 6-4, 6-2, 6-3.

Great Britain's two top women players, Viriginia Wade and Sue Barker, were beaten by determined Czechs who were more at home on the damp, heavy clay.

Wade, seeded second behind Chris Evert, made errors in unseemly clusters and grew increasingly agitated with herself as she fizzled out, 6-2, 4-6, 6-2, to Renata Tomanova, who admitted that playing on the center court gave her "goose skin."

Barker, the No. 6 seed who beat Tomanova in the 1976 final here for her biggest international title, unraveled completely in the final set and lost to ascending teen-ager Hanna Mandlikova, 7-6, 2-6, 6-1.

Two others seeded players vanished as the women moved into the third round. No. 10 Kathy May Teacher, the 1976 U.S. clay court champion, was upset by young Romanian Lucia Romanov 6-1, 6-4, and No. 14 Ilana Kloss defaulted with a stomach virus after losing the first set to Ruta Gerulaitis, 6-0.

The day's most impressive performer was Borg. He made the court look twice as large on Moore's side of the net, running down practically everything and making Moore stretch in every conceivable direction for topspin screamers he could not possibly reach.

Borg resumed practice a week ago after pulling a groin muscle that kept him off the court for 11 days. He looked slow and a bit apprehensive in his first two matches, four-set victories over Tomaz Smid and Tom Gullikson, but today he was again the incomparable zephyr who won this championship last year in 21 straight sets, losing only a paltry 32 games.

Borg was not overpowering in the first set, although he broke Moore from 40-0 in the first game and from 40-15 in the third to quickly seize command.

But from the third game of the second set he was in full cry, losing only 11 points in 10 games as he slugged breathtaking winners that left both Moore and the spectators applauding.

As a gray cloud cover seemingly descended by the minute, Borg seemed equal to the speed of light as he slid around the court, hitting with the peerless velocity and accuracy that is expected to carry him into a show down against No. 2 seed Jimmy Connors for the title a week from Sunday.

Ashe and Lendl played on court No. 3, one of the most cramped and distracting of the eight outside courts at Roland Garros, which has become almost as congested as Wimbledon because of the current surge in tennis popularity in France.

Ashe, who is exceedingly popular here despite the fact that he has never gone beyond the quarterfinals of the French championships, maintained his glacial cool in contrast to the nervous twitches and mutterings of the tall and fidgety Lendl. Ashe looked like a winner, but he was beaten decisively.