Pete Sampras, Marcelo Rios and Patrick Rafter are all facing injury worries heading into today's start of the $2.45 million Eurocard Open in Stuttgart.
The penultimate Super 9 event of the year is a key competition in the battle for places into the eight-man field at the ATP Tour World Championships in Hanover next month.
But the top three players in the world all have more pressing fitness matters on their minds after already qualifying for Hanover.
Sampras is being forced to spend what for the American seems like an eternity in cold, damp Europe this autumn.
When an early exit at the US Open and a loss in Basle last month put his year-end top ranking in danger, he reluctantly boarded a Concorde for the flight to Europe to play for more computer points.
The move paid some dividends with a title last week in Vienna thanks in no small part to the gift of a wild card from Boris Becker, no longer a full-time professional.
Sampras had to quit before his quarter-final last Friday in the Lyon Grand Prix, against German Tommy Haas due to back pains which he said were as serious as any he has faced.
Haas also benefitted on Saturday when Chile's world number three Rios stopped in the second set of a semi-final with a thigh problem.
Australian Rafter, the double US Open champion, has been playing for the past month with pains in his hip, the result no doubt of wear and tear after a full season.
Rios has been the form player of the autumn, with back-to-back victories at the Grand Slam Cup and the Singapore Open.
"The wins give me confidence," said Rios. "I was tired during the summer. But now, I'm feeling good about my performance."
Rios is also in with a chance to take back the top ranking spot from Sampras: "I was number one, then I went to number three, and now I'm coming back," the South American said. "I feel good. I'm excited about playing tournaments."
The field in the Stuttgart event is top-notch, with all of the Top 10 entered. So strong is the entry that two-time Grand Slam finalist Cedric Pioline of France missed out of the last seeded spot with his number 17 standing.
One of the top-draw figures is sure to be the revitalised Andre Agassi, now challenging for number one status after staging a comeback from outside the Top 100 a year ago.
Agassi qualified for the Hanover field with his semi-final win at the weekend in Ostrava (Czech Republic), over Wayne Black of Zimbabwe.
Though he is no longer a fulltime player, evergreen Boris Becker has received a wild card entry and the two-time champion (1990 and 1996) is sure to fill the hall when he plays a first-round match.
Officials have changed the court surface this year to Greenset carpet from the notoriously faster Taraflex in hopes of longer, more entertaining rallies.
