Under attack by old age, Reggie Jackson's hairline is in full retreat. Great plains of skin fan out from his delicate brow and spread shinily toward the distant horizon. There remains yet a widow's peak of stragglers, but they are a thin bunch and of little account.

When stragglers are all you have, however, you take fond care of them. And so, a half-hour after the Yankees beat the Orioles Friday night, Jackson sat at his locker rubbing an assortment of gels and liquids into his hair. At 34, balding men will try anything short of driving nails into each strand.

"Going, eh?" said a Yankee with more hair than Lassie.

"Hey, with the money I'm going to be making in the next four or five years, I can have any kind of hair I want," Jackson said, now laughing even as he rubbed more goo in. "Hell, who knows? I might be a blond by 1982. And I'll have Steinbrenner put it on me every day.

Jackson saw a newspaperman: "Don't write that down about Steinbrenner," he said. "I'm only kidding."

"I'll write it that way," the man said.

Reggie Jackson is at peace. What he needs so much, he now has. He is the Yankees. Billy Martin is gone. Thurman Munson is dead. Once bound to Munson and Martin by the barbed wire of respect-without-admiration, Jackson is a free man now.

Now he needs to pick no more fights with George Steinbrenner, the Yankee owner. Only kidding about the toupee, George. Now, Jackson quietly can tell advertisers to use someone else, a young player maybe, a rookie who can better use the $500. Now, Jackson can pick up a plate of food after a game and disappear into the training room, off limits to reporters having talked to players they might ignore otherwise.

On Jackson's performance in the first half of the season, the Yankees built an 11-game lead in the American League East. That lead is shrinking now, as it had to in a division that contains the Orioles, and the Yankees' fate in these last seven weeks of the season will depend in the measure on Jackson's work.

He loves the idea. He loves the heat. Nothing is more fun than seeing a great athlete who wants the moment when success or failure depends on him. Jerry West lived for the last shot . . . Muhammad Ali builds his fight dramas to a pitch of emotion that would crush lesser men . . . Joe Namath would guarantee victory on his throwing. For Reggie Jackson, life is made richer by those moments when the most is asked of him.

Through the last weeks of a pennant race, pressure comes down on a team from every angle. Perhaps alone in professional sport, baseball truly identifies its champions, for a 162-game season spread over six months is a complete examination of every player, psychololgically as well as physically. Thrown into the fire of daily combat in a pennant race, only the best and the strongest of will survive the pressure.

"I like to win," Jackson said, which is too simple an explanation for his rightful claim to that wonderful nickname, "Mr. October." Like race-car drivers whose reation time speeds up in crisis. Jackson sees better, thinks better, runs better when it means the most.

Anyone who loves baseball ought to be whipped with Frank Howard's blet if they haven't gotten to memorial Stadium for the current five-game Oriole-Yankee series. Not only is sacred "momentum" at issue, there is Reggie Jackson in full bloom. A balding sportswrtier would pay his own money to see Ali fight, Dr. J fly and Reggie Jackson walk to the place in a pennant race.

On a 90-degree night when everyone wore sort sleeves, here was Reggie in his doomsday-black, long-sleeved shirt. All blacks and grays in the Yankee uniform, a 6-foot block of muscle, his wide face foreboding in its intensity, his hands hefting a black bat as if it were a feather -- here comes Reggie Jackson walking to the plate. He doesn't glide, as DiMaggio. Jackson attacks each stride. He is Darth Vader unafraid of the Force.

And he is more. Forget Reggie the candy bar. It doesn't matter here if you like what he seems to be when his mouth is running. As Ali is honest in the ring, an honorable warrior, so is Jackson true to his game when they throw out the first pitch every night.

When you think of Jackson, you think of home runs. He can tell you how many he has. "Thirty-three and three," he said Friday night. "I have 33 home runs and we're three games up in the loss column. Those are the only statistics I care about." He knows his home runs and the standings, and that says something about Reggie Jackson that you'll never learn seeing his face on candy bar wrappers.

The guy is a baseball player.

He made a diving catch in right field the other night. Later, he went head first into second base trying to beat a force play when, because the pitch had been foulded off, there was no play at all. "Hot dog," the man said of Jackson then, but in the Yankee dugout 24 men saw an $800,000-a-year hero grubbing in the dirt like a baseball player.

When second baseman Willie Randolph pulled a hip muscle running to first base Friday night, Jackson was the only Yankee off the bench to meet his hurting teammate. "What was I saying to him?" Jackson said. "I was saying, 'How's it feel, what happened, you all right, you gonna be able to play, what's the scoop?' Willie Randolph, we can't win without Willie Randolph."

With young Bobby Brown in center field, Jackson waved his arms to catch a coach's attention. "I wanted the bench to tell Bobby where to play the hitter," Jackson said. "I wanted to take the heat off the kid. A pennant race is a lot of heat and I want somebody on the bench to take it before the kid does. All I want him thinking about is running and catching fly balls."

Jackson trotted alongside Brown and left fielder Lou Piniella as the Yankees went onto the field for the ninth inning of Friday night's game. He said something to them. Then he came back to talk to second baseman Fred Stanley.

"I said, 'Tie it up now, close the knot, shut 'em down, give it something extra," Jackson said. And when the last out was made, Reggie Jackson threw a fist of celebration at the outfield turf.