Andy Murray stunned by Albert Ramos-Vinolas in Monte Carlo

But up against Spaniard Ramos-Vinolas, the 29-year-old looked some way short of his best form as he suffered a 2-6 6-2 7-5 defeat.

Murray looked to have done enough to book a quarter-final meeting with Marin Cilic when he broke his opponent twice at the start of the deciding set, but Ramos-Vinolas came roaring back to claim a deserved and unexpected triumph, arguably the finest of his career to date.

"A year ago in Indian Wells was very close in the third (set), he had match point", Nadal said.

Murray showed trademark fight in fending off three break points at 4-4 in the decider, but could not respond when the Spaniard was in the ascendancy in his next service game. Cuevas hit a sweet forehand victor down the line on the next point and raised his arms in the air after beating Wawrinka in their first-ever meeting.

Having made a slow start in his previous match, Murray was able to seize the early initiative on Thursday, coming through a lengthy opening service game before five breaks in succession left him 4-2 up.

Ramos-Vinolas rallied back to take the next four games to level the decider and despite the Scot taking the ninth to go 5-4 up, the 15th seed closed out the match with three successive games to seal an unlikely victory.

Meanwhile, defending champion Rafael Nadal beat Alexander Zverev, spoiling the German's 20th birthday, 6-1, 6-1, and two-time champion Novak Djokovic overcame a Murray-like wobble before getting past Pablo Carreno Busta 6-2, 4-6, 6-4.

"My elbow felt pretty good", he said. "Before the match, I thought it was going to be a big test for me". That s only going to get better.

"I don't hit the ball as hard as a lot of the guys".

In a match between powerful hitters, Cilic was serving for victory at 5-4. After a long game Berdych broke back for 5-5 and then forced a tiebreaker, but the Czech player wilted against the 2014 U.S. Open champion.

Goffin downed No. 6 Dominic Thiem of Austria 7-6 (4), 4-6, 6-3, and No. 11 Lucas Pouille of France was 3-0 up when countryman Adrian Mannarino retired with a hip problem.

Former French Open champion Stan Wawrinka was also routed, with the Swiss third seed losing to Pablo Cuevas of Uruguay 6-4, 6-4.