WHERE is Bjorn Borg, now that we really need him? Out in Thailand, playing exhibitions and telling a Swedish journalist friend that he cannot find the energy to fight his way back to the top.
If Borg stays retired, he will leave men's tennis in a sour, fragmented state. Just when the world was ready to love the quiet Swedish player, and suffer through his imperfect old age, he leaves tennis to the grumps.
With Borg on the other side of the globe, the major midwinter tournament, the Volvo Masters, wound up with Ivan Lendl beating John McEnroe yesterday. People in the audience, keeping track of the Jets' demise in Miami with tiny radios plugged in their ears, extended their hometown loyalties to McEnroe for a change. But that was mainly because Lendl is also an unsympathetic figure.
This week, with New Yorkers excited over the Jets' attempt to reach the Super Bowl, it was hard enough to get excited over the annual January tennis shootout. And the hour-by-hour rumors, bulletins, denials, confirmations and speculations about Borg's future only underlined his importance to tennis in the last decade.
Since Australia stopped producing waves of sturdy champions, and since Arthur Ashe was forced to retire after heart surgery, Borg has been the mature presence at the top of the pack. If he retains his intention to stay away, he will be missed. Even though he never won the United States Open, he will be judged with the Joe DiMaggios and the Joe Louises, the strong, silent types who looked even better after they had left the arena.
The dignity of DiMaggio was all the more apparent in later Yankee generations, with Mickey Mantle throwing his helmet and Mickey Rivers playing in a fog and George Steinbrenner dismissing his managers.
Without Borg, the top level of tennis includes the four semifinalists here: the haughty Lendl, the cranky McEnroe, the entertaining but testy Jimmy Connors and the sensitive but distant Guillermo Vilas. Borg is the fifth semifinalist, the one parents could point out to a young player and say: ''That's how a champion carries himself.''
Borg wasn't interesting or exciting, but he thwacked those twohanded backhands and topspin forehands with a quiet dignity. He rarely smiled, but he rarely smirked or whined or muttered, either.
He could provide the perfect catharsis for a tennis gallery on a warm early September day at the Open. The average fan could root for an upset, get excited over Borg's losing the first set, and then be thoroughly satisfied when Borg would calmly chop, chop, chop the opponent down.
Only his exit from the big time lacked the purposefulness and grace of his career. He left the court at Flushing Meadow white as a Swedish winter, after losing the 1981 Open final with telephone death threats hanging over him. He rushed out the back door, through the greasy garbage pails behind the kitchen, and into a waiting limousine.
He never played another truly important match, running into the niggling rules of tennis that said he had to play a certain number of tournaments last year, or else submit himself to the indignity of qualifying rounds.
He didn't want the qualifying rounds and now he doesn't want the big ones, either. His business agent, Bob Kain, held a rather unusual news conference under the stands during the Lendl-McEnroe grump-out to confirm that Borg was backing away from the peak.
''He feels he's expended all the energy he has to reach No. 1 in the world,'' Kain said. ''He's in great shape. He just decided he didn't want to work. He didn't want to be a fourth-round player. He's basically an all-or-nothing guy. He was trying hard, but his heart wasn't in it.''
The irony is that Borg leaves just when the public would have adored him - the former teen angel trying to come back. But he has saved his money and doesn't need the routine anymore. He is like the railroad engine in the old children's story that wanted to leave the tracks to gambol in the buttercups. And he has found he likes the life away from the tracks.
Borg was almost never a teen-ager. He passed up the normal diversions of a Swedish childhood, quitting school at age 14 and giving up his beloved hockey because of the uncommon skill he discovered in hitting a ball against the family garage in Sodertalje.
When the teeny-boppers at Wimbledon screamed over the 17-year-old - his hair seemed more blond in those days - he seemed shy and intimidated by their passion. That was why they shrieked in the first place.
The Swedes said, ''Is e magen'' - meaning, he had ice in his stomach. But that was not totally true. In 1980 he married a Rumanian player, Mariana Simionescu, and after the 1981 United States Open they began to spend more time in their apartment overlooking the sea in Monte Carlo. He called it a honeymoon.
Last fall Borg tried to come back; he played in a few tournaments and made an exhibition tour with Connors, which guaranteed that he could not fake it. Jimbo would not let him coast, won six of seven matches, and Borg realized how hard it would be.
''I'm losing a lot of important points; sometimes I'm missing a lot of shots I shouldn't miss,'' he told Steve Jacobson of Newsday recently. ''Those shots I never missed before.''
The great DiMaggio also went through the phase when the game wasn't easy anymore, and chose to retire. Borg is 10 years younger than DiMaggio was then, but he's been at it summer and winter, in just about every time zone in the world, for over a decade.
Bob Kain is careful not to use the word ''retire'' because there is so much at stake. All the accounts are saying, ''If you're not going to play, what are you going to do for us?'' he said. No doubt Borg will still appear in public in tennis shorts to promote his accounts, will stoke himself up for a Wimbledon cameo when his ego can take it, but if the fires are out at 26, it will be hard to ever fan them again.
Where have you gone, Bjorn Borg?