The ATP say that customers who bought tickets for Sunday's ATP World Tour Finals, will get a 60% refund after the singles final between Roger Federer and Novak Djokovic was called off because of Federer's back problem.

According to the ATP website: "All ticket holders who purchased regular tickets through authorised ticketing channels will receive an automatic 60% refund. Customers will be contacted directly via their respective ticketing outlets with specific details on how they will receive their refund.

"Ticket holders for the 2014 final will also receive advanced access to purchase tickets for the 2015 tournament. Further information on how to take advantage of this offer will be sent out to all applicable customers in February next year."