Britain's Davis Cup hopes suffered a massive blow when Greg Rusedski pulled out with a heel injury.
Rusedski picked up the injury during his US Open third-round defeat to Pete Sampras.
Britain meet Thailand in a qualifying match to return to the World Group on Friday.
But with Rusedski absent, and British number one Tim Henman rating his chances of making the tie "no more than 50-50", the prospects look far from good.
Henman is still struggling with the shoulder injury that hampered him during the US Open earlier this month.
If Henman is forced to pull out, Great Britain skipper Roger Taylor will have to call on Martin Lee and Arvind Parmar to shoulder the challenge.
"At the moment my chances are no more than 50-50," said Henman.
"The arm feels a lot stronger than when I flew home from New York - but I haven't hit a ball yet and I'd be stupid to take any unnecessary risks.
"I play tennis for fun and things had not been at all enjoybale during my time in the States.
"It was tough for me to be positive."
Thailand have only one player ranked in the world's top 200, but the form of world number 31 Paradorn Srichaphan is of concern to the British team.
He beat Andre Agassi at Wimbledon, won his first tournament in August and has been steadily rising up the rankings all year.
My favorite players are Chris Evert and Jimmy Connors
Congrats to (Ball)Paradorn, the 2002 Long Island Champion, 2002 Stockholm Champion, 2003 Chennai Champion, 2003 Long Island Champion, 2004 Nottingham Champion and many many more.......