It's not a transition you see every day in sports, a man demoting himself, so to speak, from leading man to supporting cast for the good of the team. But that's the role David Robinson created for himself this year. And his ability to fill in where needed while deferring top billing to Tim Duncan has altered the perception of Robinson as a player, and is the primary reason the San Antonio Spurs are on the brink of winning an NBA championship.

Even Robinson, a man never publicly associated with selfishness, has an ego. But early this season, with his team struggling to a 6-8 start, he decided to check it. "Not only were we not playing well," Robinson said in a recent conversation, "but we didn't seem to like each other very much on the court. Nothing about it was pleasant. On a personal level, yes, you like getting the ball, the pressure, the glory. But that wasn't working the way it should."

So, Robinson did some soul-searching. An injured back had forced him to miss most of the 1996-97 season. He was bearing down on 34 years old. How much longer could he even be a top player? Suppose his back gave out on him again, forcing him out early, as had happened to Larry Bird? He talked to people close to him, and to men who had been through long careers such as Doc Rivers, who broadcasts Spurs games. "I figured, I've got a shelf full of personal trophies," Robinson said, "which ultimately don't mean anything. . . . The ego thing wears thin after a while. . . . At first, you think you can get it done all by yourself, but then you realize you can't do it. And that's where you start."

He knew the phenom who'd been drafted in his absence, Duncan, was a player of varied talents and stunning level-headedness. Some franchises go 20 years without such a player. "Right from the beginning, I saw his talents," Robinson said. "He could put a ball in a basket 1,000 different ways. I saw his talent from Day One. Late last year, he didn't know if he was really up to being the scoring man every single night. But this year, it was like, `Okay, he's ready.' So I could do other things, provide energy defensively, devote myself more to rebounding or concentrating some nights only on playing defense on another team's big man."

Once Robinson had defined and accepted this new role, he did something else we don't associate with him. He forcefully told his teammates, "If I can stick to this one role, everybody on this team had better get with the program and do what he's supposed to do, no more and no less."

It worked. Instantly, completely and for the remainder of the season. Duncan was so good, just as Robinson figured, that he didn't have to worry about scoring 30 a night. Robinson was better, as it turned out, at being Scottie Pippen than Michael Jordan. The Spurs went 31-5 the rest of the regular season, then ripped off a 12-game playoff winning streak, something Bill Russell, Wilt Chamberlain, Kareem Abdul-Jabbar, Magic Johnson, Bird, not even Jordan, had ever done. Robinson's Spurs own that record. When the Spurs win this series, either Friday night here at Madison Square Garden or in San Antonio on Sunday, Duncan almost certainly will be named the MVP of the NBA Finals. But Robinson made this whole season possible.

The testimonials roll in now because that's what happens when you win a championship. The word "soft" has been noticeably absent in describing Robinson in these playoffs. Blocking dunks and going biceps to biceps against the likes of Kevin Garnett, Brian Grant, Shaq and now Marcus Camby doesn't leave any room for "soft."

San Antonio's Steve Kerr said, "It's funny, but some of the qualities people say make him `soft' also make him a great team player. His personality is not overbearing. His ego is not out of hand. That a player of his stature could define a new role for himself like David has this season is an interesting paradox, I guess.

"One day at practice he said, `Red Auerbach never cared how many points Bill Russell scored.' I loved hearing him say that. When we need him to, he can still score, like in games where Tim gets in foul trouble. But mostly now, he figures out when and where. Fitting in is a hard thing."

Avery Johnson, San Antonio's point guard, said, "I always thought David was thrust into that role of scoring 30 a night. I think this is the way he wants to play."

Gregg Popovich, the Spurs' coach, knows that. "He's the foundation of everything we do," Popovich said recently. "He didn't score 25 a game this year, so people started to figure, `He's dead meat.' But he's still the foundation of this team in all ways."

The public may not perceive that because Robinson, who has averaged 24 points, 11.5 rebounds, 3 assists, 3.4 blocks and 1.6 steals per game in 10 seasons, had those numbers drop to 16 points, 10 rebounds, 2 assists and 2.4 blocks per game this season. Nobody would make the case he is the league's MVP anymore. He won't ever lead the league in scoring again. But winning a championship would change everything. It dismisses even the legitimate criticism about a player, and about a team.

When you win 60 games during a season and flop in the playoffs as the Spurs did on more than one occasion, it's natural and fair that the best player take some heat. Even Johnson, who adores Robinson, said earlier in the playoffs that there were postseason games in the past when Robinson didn't keep his elbows as high in the fourth quarter, when he didn't go after blocked shots with the same ferocity. It wasn't a criticism, just an astute observation.

With age and introspection, people evolve. And if Robinson can let loose, give some hard fouls and go after some people as the No. 1-A player now, fine. These are some adjustments some people never make. "Fitting in," to use Kerr's phrase, can be as hard for some as being the star is for others. That, all by itself, is almost unheard of in sports.

The Spurs are fortunate that Robinson understands the game and himself well enough to make the difficult, unselfish decisions that turn a team around and send it soaring off on a championship trajectory.

CAPTION: David Robinson, above, settled on a new role after Tim Duncan arrived.