GB could face Nadal or Federer
Great Britain could face Rafael Nadal or Roger Federer in their Davis Cup World Group play-off in September.
While Great Britain have not be seeded for Wednesday's draw, both Nadal's Spain and Federer's Switzerland are among the seeds.
Spain would represent the nightmare draw for Leon Smith's GB team, who pulled off a major upset at the weekend when they came from 2-0 down to defeat Russia 3-2.
The Spaniards, last year's runners-up, would have home advantage in any such tie and would almost certainly choose clay. However, if GB are drawn against Switzerland they will be the hosts.
Nadal is thought to be keen to return to the Spain team after missing recent ties due to injury, while Federer has played in seven of Switzerland's last eight play-off matches.
In total, GB have eight possible opponents.
Other potential ties include Austria, Croatia and Belgium - all of which would be away - and home clashes with Germany and Australia.
If GB are drawn against Japan, the venue will be decided by the drawing of lots.
The team of James Ward, Dan Evans, Colin Fleming and Jonny Marray produced a memorable comeback against the Russians in Coventry, Ward and Evans both claiming unexpected singles wins against higher-ranked opponents on Sunday to complete the upset.
British number one Andy Murray opted to skip the tie but said back in January that he would be available for the team's autumn match.
The play-off draw takes place in London at 1100 BST on Wednesday with the ties themselves to be played on September 13-15.