The first Wednesday of the Wimbledon tennis fortnight has traditionally been characterized by huge crowds and notorious upsets. The spectators arrived early yesterday - and kept arriving and arriving - but there were none of what the British press likes to call "shock results."

On a day when the chill, drizzly weather of the previous two sessions gave way to muggy, 70-degree sunshine, when gentlemen removed their jackets and ladies wore sun dresses, a single-day record 38,290 customers poured through the wrought-iron gates of the All-England Lawn Tennis and Croquet Club, which had to be shut for two hours at midafternoon.

There were plenty of matches on 15 courts for this middle-class mass of humanity and most of them went according to form.

Chris Evert and Evonne Goolagong Cawley, the leading women who played, breezed into the third round after having opening-round byes.

Evert, the champion of 1974 and 1976 and No. 1 seed, opened the day's Centre Court program by eliminating Helena Anliot, a trim, athletic 21-year-old Swede who wears her blonde hair in the braided pigtail style of an Indian princess, 6-1, 6-0.

Evert needed 20 minutes to win the first set. Goolagong needed only 19 on Court No. 1 to take part the first set en route to a 6-0, 6-2 victory over Lele Forood, 21, a Floridian who likes to serve and volley.

Goolagong, 26 and the No. 3 seed here, could be destined to become the first mother to win a singles title in Wimbledon's 101 years. She missed last year's tournament following the birth of her daughter, Kelly, but looks fit and ready to recover the title she won at age 19 in 1971.

If the tender feet that plagued her throughout the winter circuit in the United States were bothering her, she didn't show it yesterday. Lithe and enchantingly graceful as ever, she played superbly and with the sunny disposition that endears her to British galleries.

Australian Wendy Turnbull, runner-up to Evert in last year's U.S. Open, was the only seeded woman pressed, but the "rabbit" - as she is called for her swiftness of foot and anticipation - recovered to oust Sue Mappin of Britain, 8-9, 6-3, 6-4.

Tracey Austin, the No. 9 seed and youngest competitor here at 15, was much more self-assured on Centre Court than in her opening match on Court 14 and routed Betsy Nagelsen, 6-2, 6-1.

Pam Shriver of Lutherville, Md., who will be 16 on July 4, served and volleyed to a 6-0, 6-0 victory over Californian Robin Harris, who grew up on fast courts but likes to play from the backcourt.

Bjorn Borg, the men's champion the past two years, was scheduled to play the fourth match on Court No. 2, but got the day off when the first three ran long.

No. 2 seed Jimmy Connors and No. 4 Guillermo Vilas each lost a set, while No. 4 Vitas Gerulaitis, No. 5 Brian Gottfried and No. 6 Roscoe Tanner clobbered potentially troublesome opponents in straight sets.

Connors had some difficulties with his forehand, and served well only in patches, but was aggressive on the critical points in eliminating Australian journeyman Kim Warwick, 6-3, 7-5, 2-6, 6-4.

Vilas withstood a barrage of aces and occasionally was able to string together enough forcing service returns to topple sturdy John ("Saturday Night") Feaver of Britain, 6-3, 2-6, 6-4, 6-3.

Gerulaitis disposed of qualifier Jeyakumar Royappa, a wild-swinging Indian with a sometime fierce serve, 6-3, 7-5, 6-2; Gottfried volleyed beautifully in whittling 6-foot-3 Brian Teacher down to size, 6-2, 7-5, 6-3; and Tanner, who recovered from two sets down against Egyptian Ismail El Shafei on Court 6 Tuesday, went back out on the same turf to dispatch Aussie Bob Giltinan, 6-2, 6-2, 6-4.

The only seeded player beaten was the No. 12 man, Buster Mottram, the 21-year-old top-ranked Briton whose career has been marked with persistent controversy and failure in important tournaments.

Mottram's matches here have drawn an extra contingent of security police because of opposition to his membership in the National Front, and extreme rightist political organization regarded as devoted to white supremacy.

Ironically, Mottram was ousted by South African Davis Cup player Frew McMillan, who has been the target of demonstrators in the past even though he does not support the apartheid racial policy of his government.

The thoughtful McMillan, 36, is perhaps the best doubles player in the world today. He has exceptional speed of hand and reflex, volleys magnificiently, returns serve with savage consistency and is a shrewd tactician - all important virtues in doubles. Because he hits both forehand and backhand two-fisted, he has a restricted reach, which makes him vulnerable when he has to cover the whole court by himself.

But against Mottram he played well, winning the first set in a tie breaker and rolling to a 9-8, 6-4, 6-3 victory.

"It's been a bad tournament for me again . . . I couldn't get interested," said Mottram, who plans to go to Germany at the end of the week to practice on clay for an upcoming Davis Cup series against France. "At least they won't call em a Nazi there," added perhaps the least popular man in professional tennis.

The Connors-Warwick match was interesting - a valuable one at this stage for Connors, 25, who is rounding into form. He didn't know if he would be able to play Wimbledon this year when he was hospitalized for eight days in May with mononucleosis, sidelined from tennis for seven weeks.

"You try to play the early rounds the way you'd like to play the final. That's the way I look at it," said Connors, the champion in 1974 and runner-up to Arthur Ashe in 1975 and to Borg last year."If I could play the rest of the tournament the way I did today, I'd be pretty satisfied.

"I got to a lot of balls, volleyed well, and returned quite well. I had to, because Kim didn't miss many first serves until the end."

Warwick, a talented but inconsistent 26-year-old, troubled Connors with forthright serving and volleying and backhand returns chipped short and sharply angled. Connors repeatedly had to hit low, stretching volleys without much pace, which sometimes set him up to be passed.