The U.S. Open tennis championships, the richest, noisiest, most frenetic and least predictable of the world's four Grand Slam tournaments, will begin Tuesday with even more of an air of uncertainty than usual because of injuries that have forced out some stars and affected the form of others.

Australian Evonne Goolagong Crawley, who won a richly sentimental Wimbledon title in July, withdrew today because of lingering lower back spasms that have hampered her throughout this year. She notified tournament officals at 4:30 this afternoon, after being examined by a doctor in her adopted home of Hilton Head Island, S.C.

Goolagong's withdrawal -- following that of virus-ridden Billie Jean King before the draw was made last week -- opened up a dreamy path to the semifinals for 15-year-old Andrea Jaeger, the No. 8 seed who beat defending champion Tracy Austin last week in reaching the final of a tune-up tournament at Mahwah, N.J.

Other players who are nursing troublesome ailments include the No. 1 men's seed, Bjorn Borg (inflamed knee), defending champion and No. 2 seed John McEnroe (sprained ankle), and No. 2 women's seed Martina Navratilova (back spasms and frayed nerves).

Borg, the remarkable 24-year-old Swede who won his fifth French Open championship on Parisian clay in June and his fifth consecutive Wimbledon title on London grass early last month, is indisputably the best player in the world and must be favored going into any of the tournaments he enters with smartly-paced selectivity.

So it is with the $684,082 Open. Borg is the consensus pick to capture the men's singles title on Sept. 6, the day after the women's singles crown and an equal top prize of $46,000 are decided.

Borg has never won the Open, however, either its former home in nearby Forest Hills, or on the asphalt-based hard courts of the National Tennis Center in Flushing Meadows, where American's premier tournament took up residence in 1978.

New York in late summer has been Borg's personal Bermuda Triangle. The concentration and determination, fitness and skill that have guided him to more major titles than any other player has ever won at such a young age have failed him to date in muggy, smoggy, polluted Queens. Misfortune has followed him here since 1976, when he lost a rugged four-set final to three-time champion Jimmy Connors, the arch-rival he has since come to dominate.

In 1977, the last of three years that the erstwhile grass court tournament was played on clay, he defaulted with a sore shoulder he had injured while water-skiing.

In 1978, he had a badly blistered racket hand when he lost in the final to Connors, who has not reached a major final since. Last year, after Coach Lennart Bergelin tried to ease him, through the tournament without playing a night match, Borg lost uneasily to blur-serving Roscoe Tanner under the floodlights he despises.

Borg finally won his first tournament in New York when he ruled the Grand Prix Masters at Madison Square Garden in January, and he has taken a positive attitude toward the Open all year, earmarking it as the title he wants most, the one still needed to confirm his greatness.

The knee injury -- an irritated bursa sac, commonly called "runner's knee," which is incurred while jogging during his honeymoon last month -- -- caused Borg to default in the final of the Canadian Open two weeks ago. Whether or not it will affect him here remains to be seen, but he should have some reasonably comfortable run to the quarterfinals, and a possible rematch against Tanner.

Borg opens against unheralded Guillermo Aubone on the 7,000-seat grandstand court on Tuesday, and will likely play John Sadri in the second round, Bill Scanlon in the third, and Yannick Noah or Stan Smith in the fourth.

McEnroe, whose gimpy ankle did not seem to caude him too much concern as he practiced today, plays his opening match in the 19,000-seat Louis Armstrong Stadium against Frenchman Christophe Roger-Vasselin.

Tougher first-round opponents await No. 5 seed Vitas Gerulaitis, runner-up last year to his Long Island neighbor McEnroe, and No. 8 seed Eddie Dibbs. Gerulaitis plays Californian Vince Van Patten, an actor-pro who has improved rapidly, in the opening stadium match. Dibbs faces veteran Bob Lutz, recent winner of two tournaments, in the last match of opening night.

Tuesday's evening session will begin with Austin, who last year became the youngest U.S. championship ever at 16 years, nine months, playing talented and athletic Texan Anne Smith, an aggressive serve-volleyer.

Austin remains the tournament favorite to defend her title, but she has by far the sternest draw of any of the top women. She will likely have to play, in addition to Smith, Rosemary Casals, Dianne Fromholtz or Pam Shriver (the re-ascending 18-year-old runner-up of 1978) in the quarterfinals and Chris Evert Lloyd, the four-time champion she dethroned in last year's final, in the semifinals.

The bottom half of the women's draw is much weaker than the top, especially with Goolagong's withdrawal, Jaeger's chief to reaching the semifinals would seem to be over-the hill Betty Stove.

Jaeger is the youngest player ever seeded in the Open, the youngest ever to crack the world top 10, and is a good bet to reach the semis against Navratilova, Wendy Turnbull, or Hana Mandlikova, the gifted teen-ager who beat Jaeger in the Mahwah, N.J., final on Sunday.

Like Borg, Navratilova never has won the U.S. Open, but this does not appear to be the two-time Wimbledon champ's year. The expatriate Czech left-hander is beset by physical and personal problems, exacerbated by the fact that her parents and sister recently returned to Czechoslovakia, apparently unable or unwilling to adjust to fast-paced American life and Martina's life style.

Most experts think that Navratilova will not be a factor and that if Austin and Evert reach their anticipated showdown in the semis, the winner of the match will go on to win the title.

But then again, this is the U.S. Open: messy, loud, blatantly commercial and schizoid as New York City itself. Planes roar overhead from neighboring La Guardia Airport, gentility gets mugged daily, players have to acclimate to day, night and twilight conditions, and anything can happen.