'I'll be back' vows Nadal after injury halts US Open repeat bid

New York: Devastated Rafael Nadal vowed the knee injury that forced him out of the US Open semi-finals on Friday won't stop him chasing more Grand Slam glory.

The Spaniard, his world number one ranking still safe, said the trouble was the familiar tendinitis he's dealt with for a decade -- unpredictable but not career-threatening.

"I know what I have," he said after limping off Arthur Ashe Stadium having lost two sets to third-seeded Argentine Juan Martin del Potro. "I know what is going on with the knee. I know how I have to work to be better as soon as possible."

But it was clearly galling for the player famed for his fighting spirit to hobble out of a second Grand Slam of 2018, having retired in the fifth set of his Australian Open quarter-final against Marin Cilic with a torn inner hip muscle."It's not about losing, it's about not having the chance to fight for it," he said.

"I'm having two great years," added Nadal, who was trying to complete a French Open-US Open double for the second straight season. "Last year was a fantastic year. This year

has been a fantastic year until this moment. I lost four matches. Two of them I had to retire." The frustration isn't new for Nadal.

"I feel that I fought all my career against these kind of things too," added the 32-year-old, who has missed at least eight Grand Slams due to injury since his major debut at Wimbledon in 2003.