World number one Andy Murray's frustrating start to the season has continued after being knocked out of the Madrid Open by Borna Coric in straight sets.

The 2016 finalist beat wildcard entrant Marius Copil on Tuesday in his first outing in the Spanish capital, but he again failed to reach anything near his top form as he fell 6-3 6-3 to Coric this afternoon.

Coric broke his opponent's serve three times in a row in the opener, using his big forehand to trouble the Scotsman and taking it with his third set point.

Murray's disappointing clay-court run, which has seen him fall short in Monte Carlo and Barcelona, showed little sign of improving in the second set as he failed to break an impressive Coric.

Coric found a breakthrough in the eighth game with the only break, before serving out the contest to set up a quarter-final meeting with either Grigor Dimitrov or Dominic Thiem.