ANDY Murray admits he doesn't have a clue who he will be playing on day one of Great Britain's Davis Cup semi final against Argentina in Glasgow this weekend.

A number of permutations remain open until an hour before today's draw - not least of which is the World No 2's opening day opponent.

As Britain's No 1 singles player by the rankings, competition rules mean that he automatically faces the weaker of Argentina's two singles players. What is normally a straightforward process is complicated by the fact that Del Potro - only recently back in top form after wrist problems - is only the third highest-ranked player in the Argentine squad.

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This presents visiting captain Daniel Orsanic with the dilemma of pitching Del Potro into a re-match of the recent Olympic final on day one, or preferring his lowest singles ranked player, Leonardo Mayer - albeit ranked World No 21 as recently as June last year - to his current No 1, Federico Delbonis. He may conclude that Del Potro's capacity to at least to deplete the younger Murray sibling's resources, even if the rubber ends in defeat, is a price worth paying.

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“I don’t know to be honest as they have different options for what they want to do," said Andy Murray. "It’s kind of like most tournaments for us just now. You don’t find out until a day or two before who we play. Tomorrow we will find out and get ready to play whoever it is on Friday but it doesn’t matter to me who plays the first day. I’ll prepare the best I can.”

Captain Leon Smith is at the horns of his own dilemma as he aims to lead Britain to a repeat success in this trophy which is unprecedented in the modern era. He faces a tough call between Dan Evans and Kyle Edmund - two men who have risen to the top 60 in the rankings and are coming off storming US Open runs - for his second singles player. Whoever he picks, the Scot has called for the whole-hearted backing of a Glasgow crowd as he takes on a team which he rates as more difficult opponents than anyone Britain faced on their glory run of 2016. The final, should they get there, will either be a home tie against Croatia or away match against France.

"It [the crowd] helped last year and it will help this weekend," said Smith. "It’s needed as Argentina are very, very strong and on paper maybe stronger than what we faced last year - Del Potro fit and healthy is definitely as Andy said one of the best players in the world - Australia wouldn’t have had that last year in their team. Delbonis is so experienced, [Guido] Pella had a decent ranking for a while now, Mayer was at 21 in the world 18 months ago. It’s a strong team."