Indian Wells, United States (AFP) - World No. 1 Andy Murray crashed out of the ATP Indian Wells Masters on Saturday, sent spinning in straight sets by Canadian qualifier Vasek Pospisil. Pospisil, ranked 129th in the world, triumphed 6-4, 7-6 (7-5), sealing the biggest win of his career on his fourth match point to the delight of a stadium court crowd won over by the underdog's aggressive serve-and-volley style.

For Britain's Murray, it was yet another disappointing performance in the California desert, where his best showing is a 2009 runners-up finish to Rafael Nadal.

Last year Murray was bundled out in the third round, but he was hoping for much better as he arrived fresh off his 45th career ATP title in Dubai.

"I don't know exactly why it is, because in practice here normally I play pretty well," Murray said. "And then some years I played well. Some years it just hasn't quite happened for me. I don't know exactly why that is."

Murray was particularly disappointed to have dropped the first set after twice going up a break. But he hurt his own cause with seven double-faults, part of a poor serving night that he said was key to the defeat.

Pospisil had never beaten Murray in four prior encounters. The 26-year-old, who defeated Taiwan's Lu Yen Hsun in the first round as Murray enjoyed a bye, notched his fourth career victory over a top-10 player and his first since 2014.

The Canadian, a Wimbledon doubles title winner with Jack Sock, was ranked as high as 25th in the world three years ago, but plummeted to as low as 135th in the world during a tumultuous 2016.

Late last year, he began working with Australia's Mark Woodforde - and he gave a shout-out to his new coach on court after wrapping up the biggest win of his career in one hour and 51 minutes.