Wimbledon champion Martina Navratilova, who ruled the roost on the women's indoor tennis tour this winter, won its climactic playoff today.

Mature and self-controlled at age 22, the powerful expatriate Czech left-hander defeated 16-year-old Tracy Austin, 6-3, 3-6, 6-2, to capture the $275,000 Avon Championships at Madison Square Garden.

In so doing, Navratilova vividly demonstrated for 13,752 live spectators and a national television audience the ability to think and correct technical flaws in midmatch that has helped transform her from an exciting but undisciplined raw talent into a resourceful and self-assured champion.

Navratilova earned the $100,000 top prize the hard way, battling both a switt and fast-improving opponent and her own fitful backhand.

After overwhelming the 5-foot-4, 115-pound Austin with an explosive barrage of heavy artillery in the first set, Navratilova unwittingly started rushing her backhand, overanxious to beat a path to the net, which she rules with deadly volleys.

Suddenly, she was beating herself, playing right into Austin's strength -- steadiness in the back court -- by spraying approach shots here, there and everywhere. She became so erratic on the backhand side that she almost endangered the potted plants deployed around the court, making them fear for their fronds.

Her slice and sidespin approaches floated long or wide. Her more assertive topspin screamers hummed into the net. She "just couldn't find it," as the tennis players say, and so exasperation mounted in a face that had been brimming with confidence minutes earlier.

If the pre-1978 Navratilova's backhand had gone to hell in a handbasket this way, she would have followed soon enough -- unraveling in an emotional poof of anger and self-pity, fueled by resentment of the crowd screaming loudly for the underdog Austin.

But the onetime diamond in the rough is now finely cut and polished, and today she sparkled. There were hangdog looks and dropped rackets, but they represented not despair, only a determination to make the necessary adjustments.

"I was shaking my head because I was missing a lot of shots, not for the hell of shaking it," Navratilova said after righting herself, and regaining control of the 99-minute match.

"I was missing all those backhands, and I was just trying to figure out what I was doing wrong, because I knew it was technical. I was rushing into the ball, running in to the net almost before I hit the ball.

"So I just made myself slow down and tried to figure out what the problem was," she continued. "It was constructive thinking. It wasn't just dejection or frustration.

"That's the difference. Two years ago I probably wouldn't have figured it out, and would have just kept on doing the same thing. But this time I changed it up a little bit, and it paid off. I hung in there.

"... I knew I couldn't just stay on the baseline. I had to keep trying the approach shots, and either I would get it or I wouldn't. I was worried for awhile. But I've done a lot of work on my game, so I didn't think it was all going to go to pot in one match."

In the first set, the muscular 5-8, 145-pound Navratilova, winner of five of eight tournaments and $271,500 so far this year, had too much weight and variety of shot for Austin. She won the first eight points of the match, and seemed eager for a rout.

"I'm going to try to play my game more than hers. She's going to stay back and hit the ball but I feel I can pretty much control what's going to happen if I serve and volley well and don't make too many unforced errors," Navratilova, winner of four straight meetings with Austin since losing to her in the final of the Avon tour inaugural at Washington in January, said before the match.

Her assessment was correct, for when she was playing well, she smothered "little Tracy."

Austin has expanded in size, savvy, and strength since she first appeared at Wimbledon two summers ago, a schoolgirl of 14 in braces, pigtails, and oversized pinafores. She is a formidable opponent for anyone, remarkable in her speed afoot and anticipation. But even she could not run down the explosive volleys, overheads, and ground strokes that Navratilova was detonating in the first set.

Jerking Austin out of position with menacing serves deep to her twofisted backhand, Navratilova opened up the court for slashing put-away volleys and smashes.

But in the second set, Austin started anticipating that serve and moving to cover it as Navratilova tossed the ball. Martina's attempts to keep her honest with a few serves down the middle to the forehand failed -- "I just couldn't get that one to tail away from her" -- and so Austin began cranking some winning returns and wonderful passing shots to the small areas of the court open to her.

Then Navratilova's backhand went haywire, and Austin was right back in the match, keeping the ball in play and letting her opponent make the errors. Even Navratilova's 84-year-old grandmother, visiting her from Czechoslovakia and sitting courtside, began to cringe.

After Austin broke serve in the fourth game with an angled backhand cross-court pass, Navratilova had chances to get back in the seventh and ninth games, but made nine of her total 27 unforced backhand errors.

At the start of the final set, she took a deep breath, then served a good game. She had five break points on Austin in a marathon second game that went to deuce eight times, but again missed backhand approaches on all of them.

"I thought she might get a little shaky after that," said Austin, whose $52,000 check as runner-up brought her total earnings in five months as a pro close to $200,000.

But it was not to be.

Navratilova grittily served a strong game -- four mighty serves from 0-15, an ace on the game point -- to lead 2-1, and broke in the next game for a 3-1 lead.

Austin did break back to 3-2 after two deuces, but Navratilova had figured out and solidified her backhand by then. Instead it was Austin's forehand that crumbled in the end, causing her as many headaches as she lost the last four games as Navratilova's backhand had given her earlier.

Ever since she won this tournament last year -- when it and the women's circuit were sponsored by Virginia Slims -- Navratilova has thought of herself as the No. 1 player in the world. She went on to beat Chris Evert in the Wimbledon final, but lost the No. 1 ranking, perhaps unfairly, with three late-season losses to Evert, who wound up 1978 with a 56-3 record.

This time, with the soon to be wed and therefore preoccupied Evert ousted before the semifinals, there could be no doubt that Navratilova is No. 1, at least for the moment.

"I've won five tournaments and twice as much money as anybody else so far this year.I have a big start on everybody but I have to keep it up if I'm going to be recognized as No. 1 at the end of the season, when it counts," she said, realistically. "If I keep playing the way I have been, nobody can take it away from me."