Andy Murray suffered a surprise exit at the Barcelona Open, losing in straight sets to big-serving Canadian Milos Raonic.

The 6ft 5in 21-year-old from Ontario, who crushed sixth seed Nicolas Almagro in the last round, headed into the match having never beaten a top-eight player but rarely looked overawed en route to a 6-4 7-6 (7/3) triumph.

He endured a minor blip when serving for the second set, allowing second seed Murray his first break of the match, before breezing through the tie-break to clinch the biggest win of his fledgling career in one hour and 44 minutes.

Raonic will face third seed David Ferrer or seventh seed Feliciano Lopez in the semi-finals, the Spanish duo meeting in the second quarter-final in Catalonia.

Raonic's fierce forehands helped him bring up a break point in the opening game, which Murray survived, and two aces from the world number 25 swiftly levelled things up.

The first set followed a similar pattern - Murray tested on serve and Raonic holding with ease - until game seven, when a loose drop shot from the Scot resulted in a second break point for the youngster, and this time he capitalised to go 4-3 up.

Raonic comfortably held again to move within a game of the set and then, after Murray had dug out the hold with the help of an ace, the Canadian brought up three set points with his ninth ace and duly took the first with a forehand winner.

Murray showed all his battling qualities as the match headed into a second-set tie-break.

But Raonic cruised into a 5-1 lead and, although Murray engineered a chink of light by taking his two points on serve, there was no way back.