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The make-up of Great Britain's Davis Cup final team will become a lot clearer on Tuesday with captain Leon Smith due to name his provisional team and Aljaz Bedene fighting his case for eligibility.
The British number two, who has previously represented his native Slovenia, has fallen foul of a rule change banning players from competing for two different countries.
His case will be heard at an International Tennis Federation board meeting in Prague, and Smith is likely to delay naming his team for the clash with Belgium beginning a week on Friday until after the outcome is known.
Should Bedene be successful, he will know he has the support of both Murray brothers after Andy followed Jamie in backing the 26-year-old's inclusion.
Murray, who opened his ATP World Tour Finals campaign with a 6-4 6-4 victory over David Ferrer in London, said: " If he wins his appeal and is able to play, then, if I'm the captain, I'm picking my strongest team to try and win."
Smith certainly is not short of options. As well as Bedene; James Ward, Kyle Edmund and Dan Evans are all in contention for the second singles spot.
Edmund and Evans pushed their cases by both winning Challenger Tour titles on Sunday but Ward has the most experience.
In all likelihood, Smith will name at least two of the trio in the team and may take all three to Ghent to fight it out in practice. He has the option to change his line-up up until the draw a week on Thursday.
Murray was very happy with his form having feared he might be a little rusty on hard courts after spending much of the build-up preparing for Davis Cup on clay.
In his second match at the O2 Arena on Wednesday, Murray will play Rafael Nadal, who despatched an out-of-sorts Stan Wawrinka 6-3 6-2.
Wawrinka made 35 unforced errors and was criticised by several pundits for his attitude.
The world number four insisted he had been trying but said: "I t's a really bad match. Bad behaviour in the second set, going too fast. Things that are not too great on myself. Hopefully I can put it back together."
It was an encouraging performance from Nadal, who has struggled for form and confidence this season but is feeling more like his old self again.
The 29-year-old has kept a sense of perspective, saying: " I was not happy the way that I was working on court. At the same time, it's only a game. When you see all the things that happen sometimes around the world, that's nothing."
Jamie Murray and John Peers will hope to make it two wins from two against Rohan Bopanna and Florin Mergea on Tuesday while the main event sees Novak Djokovic take on Roger Federer.
Djokovic has lost just one set in 23 matches since beating Federer to win the US Open two months ago, but the Swiss said: " I don't think I'm that far off."