The 25-year-old from the Black Sea resort of Sochi greeted his elevation with an understatement: "I'm not at my best at present."
Regarded as the most exclusive club in sport since Ilie Nastase became the first world No 1 on the computer in August, 1973, a quirk in the ATP Tour rankings has introduced an element of farce.
Based on players' 14 best results over a 52-week rolling period, the ATP Tour rankings allow competitors to rise or fall without even playing. Pete Sampras, the five-times Wimbledon champion and the year-end No 1 for a record six consecutive seasons, has been at the top for all but three weeks so far this season in spite of missing tournaments because of exhaustion or injury, including the Australian Open in January.
Kafelnikov, who light-heartedly thanked Sampras for missing the Australian Open after being presented with the men's singles trophy at Melbourne Park, failed to capitalise further at the Guardian Direct Cup indoors in Battersea Park in February. Arriving in London with the Rotterdam title, having defeated Britain's Tim Henman in the final, Kafelnikov came within one match of supplanting Sampras as the world No 1, only to lose to Sweden's Thomas Johansson in straight sets in the quarter-finals.
Carlos Moya, of Spain, took everybody by surprise, not least himself, by becoming the 15th world No 1 in March on the strength of a place in the final in Indian Wells, California, where he was defeated by Australia's Mark Philippoussis. Moya's reign at the top lasted two weeks, Sampras overtaking him by reaching the quarter- finals of the Lipton Championships in Florida.
Kafelnikov has not won a match in his six ATP Tour events since Battersea. In Prague last week, the Russian was defeated in the first round by Australia's Richard From-berg, but the result did not stop Kafelnikov from moving 15 points ahead of Sampras, who took the week off to nurse a back injury. The American is four weeks short of overtaking Ivan Lendl's record total of 270 weeks at No 1.
The top two are absent from this week's German Open in Hamburg, Kafelnikov having picked up a virus (though not from the computer), and Sampras easing his dodgy back towards Rome, where both are due to play in the Italian Open next week. By then Moya may have returned to the top, or the Dutchman Richard Krajicek may have become the 17th world No 1. Both need to win the Hamburg title and defeat opponents whose ranking afford the necessary bonus points.
Next year there will be a new ranking system, a year-long race for No 1 from January to November similar to the current race to the ATP Tour Championship in Hanover. It will replace the rolling 52-week period, which will be retained for the purpose of seedings.
The ATP Tour, which hopes the new system will be easier for the public to follow, has yet to find a suitable name to convey that the weekly lists are standings, with rankings reserved until the race is over. Critics of the change argue that regular movement at the top of the list, with little known players flitting in and out like fireflies, will devalue the status of the rankings. Supporters of the change point out that other sports have league tables, and the sight of Wimbledon, for example, at the top of the Premiership in August does not necessarily mean they will be there when the trophies are presented.
Rainer Schuttler, who defeated Henman in the final of the first ATP Tour event this year in Qatar, would have led the standings on 11 January, but only sustained form would have kept him there.
Kafelnikov's triumph at the Australian Open, the year's first Grand Slam tournament, gave him the points and momentum to keep his name at the top of the race to Hanover for most of the season so far. Success at the four Grand Slams is the true measure of excellence, the reason why the cream will always rise to the top.
That is why Kafelnikov, in spite of his recent lapses, is entitled to say: "I think that I merit to be No 1."
SIX FALSE STEPS TO THE TOP
THE FOIBLES of the ATP Tour ranking system, based on players' best 14 results over a rolling 52-week period, enabled Russia's Yevgeny Kafelnikov to become the world No 1 yesterday, in spite of losing his last six opening tournament matches since being denied a place in the semi-finals of the Guardian Direct Cup by Sweden's Thomas Johansson indoors in Battersea Park on 26 February.
8 March - Indian Wells, California (concrete): lost to Gustavo Kuerten 6-0, 6-7, 3-6.
15 March - Key Biscayne, Florida (concrete): lost to Vince Spadea 7-6, 6-7, 2-6.
5 April - Estoril (clay): lost to Andrei Pavel 3-6, 6-2, 3-6.
12 April - Barcelona (clay): lost to Franco Squillari 2-6, 4-6.
19 April - Monte Carlo (clay): lost to Ivan Ljubicic 1-6, 2-6.
26 April - Prague (clay): lost to Richard Fromberg 4-6, 6-2, 4-6.