EFEInternational Sports Desk

Spanish tennis great Rafael Nadal hailed the key role played by his uncle and coach throughout his career but said he did not know whether he would be able to capture a 15th major title.

"I don't know when I'll be able to win another Grand Slam, or if I'll be able to win one," Nadal said Thursday in New Delhi, where he is competing in the International Premier Tennis League, a team exhibition event being played across five venues in Asia this month.

The 29-year-old Nadal, who failed in 2015 to win a Grand Slam singles title for the first time in a more than a decade, also responded to American former star and current TV commentator John McEnroe's recommendation that he give himself a late-career boost by switching coaches.

"Without Toni (Nadal), none of this would've been possible. I feel very fortunate to have someone from my family be my coach. For me, it's a big advantage," the Spaniard said.

Nadal, whose only titles this year came at minor events in Hamburg, Stuttgart and Buenos Aires, noted that his form improved at the end of the season with runner-up finishes in Beijing and Basel.

"Things were much better over the last three months, although 2015 wasn't my best season," the current world No. 5 said.

"I'm pleased with how I'm playing now. I have to stay on the same track through the end of the year. I improved in the last few tournaments. I'll have to work to maintain my level and start winning again," Nadal, whose haul of 14 Grand Slam men's singles titles is second only to Swiss arch-rival Roger Federer, said.

The Micromax Indian Aces, Nadal's team in the IPTL tournament, thrashed the Philippine Mavericks 30-12 in New Delhi on Thursday.

The Spaniard and other top players, including Federer and fellow Swiss Stanislas Wawrinka and Britain's Andy Murray, are playing that event as part of their preparations for tennis' next Grand Slam tournament, the Australian Open, which gets underway in mid-January.