Davis Cup organisers admit selling tickets for the revamped competition is proving a challenge with less than two weeks to go.

Eighteen national teams will head to Madrid for the first edition of the week-long, World Cup-style event, which begins on November 18.

The new format, which has largely replaced the traditional home-and-away fixtures, was controversially approved at last year’s International Tennis Federation AGM despite vociferous opposition from a number of current and former players, officials and fans.

Barcelona footballer Gerard Pique’s Kosmos company is the financial muscle behind the event having pledged to invest three billion US dollars (approximately £2.3billion) over 25 years.

But efforts to recoup some of that money through strong ticket sales are proving problematic.

The good news for organisers is that both of Spain’s group ties, against Russia and Croatia, have sold out the main arena, which seats more than 12,000 spectators.

But, behind the host nation, Great Britain’s total of 3,000 tickets sold to fans for their clashes with the Netherlands on November 20 and Kazakhstan the following day is the most for any country.

Of the 25 sessions across the three arenas, ticket sales have only reached 50 per cent for nine of them, although a further five are close.

A spokeswoman for Kosmos told the PA news agency: “We are happy with ticket sales for the afternoon sessions and from Friday until Sunday (quarter-finals, semi-finals and final) but it’s much more difficult to sell tickets for morning sessions, as happens in all tournaments.

“We are working with the 17 embassies in Spain in order to reach international communities living in Spain. We have economic prices. The cheapest ticket costs 25 euros and you can see a tie (comprising three matches).”

The first two morning session ties in the main arena, between Argentina and Chile on November 19 and Serbia and Japan the following day, both have more than 8,000 tickets still available.

The disappointing sales come despite countries naming strong teams, which was the main objective of the change of format.

Six of the top 10 will be in Madrid, including Rafael Nadal and Novak Djokovic, with Germany’s Alexander Zverev the only eligible player to opt against making the trip.

There are also six players ranked between 10 and 20 and eight between 21 and 30, while Great Britain’s team includes former world number one Andy Murray.