A degree of confusion appears to be afflicting the ATP Tour. The rankings computer is regurgitating world No 1s at an astonishing rate and even the most attentive competitors appear to have become prone to lapses of memory.
The other week Pete Sampras was taken aback when asked about his prospects of collecting a third consecutive title in Indian Wells, California. "I don't think I've won the tournament two years in a row, have I?" was his response.
While Sampras is hardly likely to experience amnesia when quizzed about the possibility of a fourth successive Wimbledon singles championship in July, every title counts. His successful defence in Indian Wells 12 months ago, for example, was the first of five victories which enabled him to end the year as world No 1 for the third time in a row.
Andre Agassi needs no prompting to recall that his win against Sampras in the final of the Lipton Championships here on the tip of Florida last year completed his elevation to No 1 for the first time.
A change at the head of the game was then still a rare occurrence. Since the start of the year, however, there has been a shuttle service. Sampras was replaced by Agassi, who was supplanted by Thomas Muster, only the 13th player to become No 1 since rankings began in 1973.
The Austrian king of clay courts lasted a week before making way for Sampras, who then failed to repeat his form in Indian Wells, losing to the Dutchman Paul Haarhuis in the quarter-finals.
This allowed Muster to rise again, and here he is yet to win a tour match while reigning as the No 1. Having exhausted their jibes about Muster's feet of clay when he was promoted the first time, Sampras and Agassi must now accept that their own shortcomings have helped to lift him back to the summit.
"It's not like I have some sort of vendetta against Thomas," Sampras said. "He is the best player in the world on clay. As far as him being the best player on anything but clay, I don't quite swallow that quite as well. He had a phenomenal year, winning the French Open and 10 other clay-court tournaments. I didn't do well in Australia, and it just so happens that he snuck up and became No 1.
"It really just comes down to the end of the year. That is when you add and subtract all of your points. The final ranking is the true indication of who the best player in the world is.''
That thought will be running through several minds. Currently, Muster leads Sampras by just 19 points and is only 608 points ahead of the fourth- placed Michael Chang, who is closing in on Agassi after defeating him in the quarter-finals at Indian Wells, and has Boris Becker at his heels.
All of which delights the ATP Tour's chief executive, Mark Miles. "I'm not apologising for Thomas Muster being No 1 for a second. Just look at his record over the previous 52 weeks," Miles said. "I'm absolutely thrilled - how could you not be? - that we could actually have a real race of four or five persons split between the United States and Europe. They are all great champions, and they are different, with different styles of play and different personalities.''
The women's tour would welcome similar activity, and trusts that Iva Majoli and Anke Huber will continue to make progress and generate a serious challenge to Steffi Graf and Monica Seles. Seles's absence from the Lipton, because of a shoulder injury, is the only disappointment for the organisers of the tournament, which offers total prize-money of $4.1m (pounds 2.7m).