I don't know if I'll ever win a grand slam: Murray

British tennis ace Andy Murray, who crashed out of the US Open on Sunday, says that though he doesn't know if he will ever win a Grand Slam title, he would still work hard for it.

"If I give 100 per cent, try my best, physically work as hard as I can, practise as much as I can, then that's all I can do," The Independent quoted Murray, as saying.

"I don't know if I'll win a Grand Slam or not, but I'll give it my best shot," he added.

Murray's quest for an elusive major is over for another season after he limped out of Flushing meadows after being stunned by Stanislas Wawrinka 7-6, 6-7, 3-6, 3-6 in the third round.

The 23-year-old, whose fitness is usually one of his great strengths, admitted that he was struggling physically in the third and fourth sets.

"I got frustrated with that. I haven't been in that position for a very long time. Maybe I felt like my chance of doing well here was slipping away. I've worked very hard to give myself a chance of winning tournaments. When I was struggling physically, I got disappointed," Murray said. 

Despite the US Open being his favourite Grand Slam, Murray has only passed the fourth round once - in 2008.