Roger Federer and Serena Williams have pulled out of this season's International Premier Tennis League (IPTL). The multiple Grand Slam champions were due to play in the final leg of this year's event in Hyderabad from December 9 to 11. Federer was to play for the Indian Aces while Williams was to appear for the Singapore Slammers.

"We have had challenges this year, and we were hoping to get past them," Mahesh Bhupathi, founder and managing director of IPTL, said in a statement. "With the current economic climate in India and the uncertainty of spending money, I reached out to both Roger and Serena to explain the situation. They have been both been very supportive of the IPTL the first two seasons and we look forward to bring them in future years."

The withdrawal of Federer and Williams robs the tournament of its sheen. It had already been reduced to a three-city affair from the five cities that had featured on the calendar in the previous two years. There had been plenty of excitement surrounding the appearance of Federer and Williams, especially since both haven't played competitively for a few months now. Federer has been out since July following knee surgery while Williams last played at the US Open, following which she has stayed away from the circuit with a shoulder injury. She was scheduled to appear in the Singapore leg starting today.

The New York Times quoted Federer's agent Tony Godsick saying his withdrawal was due to "some problems and uncertainties surrounding the IPTL". He added that Federer "hopes to play in future years if the IPTL continues". Though the organisers weren't available for further comment, there has been speculation of the IPTL batting financial concerns. The significant reduction in the field along with a number of high-profile players being unavailable this year has led to speculation about the future of the event itself. In previous years, besides Federer and Williams, the likes of Andy Murray, Novak Djokovic and Rafael Nadal have played in the IPTL.

ESPN learns that ticket sales in Hyderabad for the upcoming weekend have been slow as well, though that may be because of the cash crunch resulting from the government's decision to demonetize high-value currency notes. With world number 5 Kei Nishikori also ending his commitments for the year by appearing in the Tokyo last weekend, the highest ranking men's singles player left in the tournament is world number 10 Tomas Berdych of the UAE Royals.