He’s known to millions of soccer fans worldwide simply as Kaka. That’s the Brazilian way — to use a one-word nickname. Quite often, the words mean nothing: Pele was never able to explain the origin of his nickname. But we know how Kaka got his name: His younger brother, Rodrigo, couldn’t pronounce Ricardo properly, so in early life, Ricardo Izecson dos Santos Leite — a name that not one soccer fan in 10,000 would recognize — became Kaka.

Later in his life, Kaka moved to Europe to play in Italy with AC Milan. And last year, at the age of 25, he became the most famous player on the planet. For Kaka, 2007 was truly an annus mirabilis: Not only was he voted FIFA’s Player of the Year, but he also claimed all the other most prestigious “best player” awards — those bestowed by the magazines France Football and World Soccer, by UEFA (the European soccer federation), and by FIFPro (the international organization of professional soccer players). He was also voted the best player in the Italian Serie A. Rarely, if ever, has a player received such unanimous acclaim. And what sort of a player is Kaka that he should be so widely admired? I’ll refer you to yet another award he won last year, that given by the International Federation of Football History and Statistics, which voted him (with 241 votes to the 90 received by the runnerup) “the world’s best playmaker.” Playmaker: The central figure in his team’s play, the midfield creative genius with the ability to think and act instantly, to pass accurately, to dribble past opponents. Kaka does all of that with stylish ease. He does more, too: He scores goals. Kaka was the top scorer in the 2007 UEFA Champions League, his 10 goals leading Milan to the title.

That is Kaka, the complete player on the field. Off the field, Kaka is a quiet, devoted pro among the sport’s often showy celebrities, a devout Christian married to his boyhood sweetheart.

A wondrous story, a true fairy tale — but it’s one that has suddenly been interrupted. The “what have you done lately?” reality has caught up with Kaka. All those titles and awards, that was last year. Here we are, not even two months into 2008, and already Kaka’s “world’s best” title is slipping away from him.

Suddenly, Kaka seems, at best, to be the world’s no. 3, because two new (and younger) players have emerged: Cristiano Ronaldo, the Portuguese who plays for Manchester United (today is his 23rd birthday), and Barcelona’s Argentine, Lionel Messi (age 20). There are similarities in the three players: All have the flair — the “Latin” flair — common to players from South America and from Spain, Portugal and Italy. Kaka and Messi are South Americans, while Ronaldo is from the island of Madeira. Ronaldo is having a superb season with Manchester United, a season that can be measured by the league-leading 19 goals he has so far scored. But the mere number does not do him justice; the goals have often been spectacular, have often been scored at crucial moments, and have been scored in a bewildering variety of ways, from open play with either left foot or right foot, from free kicks, and from powerful headers.

That Ronaldo should be able to triumph in England — where flair tends to be regarded as hot-dogging — is remarkable. He has been frequently criticized for being a prima donna, for “going to ground too easily” (i.e. diving), and for exaggerating his step-over dribbling moves. Opposing defenders like to give their own fans a reason to cheer when they foul Ronaldo, which they do, frequently. The notoriously lenient English referees typically ignore many of those fouls.

Ronaldo’s answer has been to play with an individual brilliance that makes a mockery of the criticism. Adding to his prolific scoring is his growing maturity as a crafty playmaker. The world’s best? Quite possibly — for no one is playing any better at the moment — until one considers Messi, who is a rather different sort of player. Where Ronaldo and Kaka are both 6-feet-1-inch, handsome, bronzed athletes, Messi is a pale-faced youth who measures only 5-feet-7-inches. Too small? Not for a genius: Diego Maradona was even shorter than Messi. And it is with Maradona that Messi is often compared. Like Maradona, Messi is left-footed, a comparative rarity among players that adds an extra sense of mystery to their moves. Maradona has stated that he sees Messi as his heir, and last year Messi emphasized the similarity with a goal that he scored for Barcelona against Getafe in the Spanish Liga. It was almost a carbon copy of the goal that Maradona scored after dribbling through the entire English defense in the 1986 World Cup — a goal that is often hailed as the greatest in World Cup history.

I do not see another current player with the extraordinary moves — the feints, the changes in speed and direction, the close ball control — that Messi has. One telling point that underlines Messi’s skills and confidence is this: As the form of his teammate, the great Brazilian Ronaldinho, has slumped this season, it is Messi — at 20 years of age — who has become the key player on this star-studded Barcelona team.

For the moment, Kaka can justly claim to rule the world of soccer, not simply because of all those honors, but also because he has proved a winner in international soccer, leading Milan to wins in the UEFA Champions League and the Club World Cup. Neither Ronaldo nor Messi has that sort of experience. That could change this year, for both Manchester United and Barcelona are still alive in the Champions League, giving Ronaldo and Messi a chance for international glory. Or maybe not: Another team still in the competition is Milan, with its supreme playmaker, Kaka.

Regrets: This column is my last for The New York Sun, after a four-year stint. My thanks to my readers, to those who have been pleased, and to those who have been displeased. It has been a most enjoyable four years.