Photo: Susana Vera/Reuters

World number one Andy Murray's slump in form continued with a 6-3, 6-3 defeat to lucky loser Borna Coric in the third round of the Madrid Masters on Thursday.

Murray has now failed to reach the quarter-finals in any of his last three Masters series events, as well as suffering a shock fourth round exit at the Australian Open to Mischa Zverev in January.

World number 59 Coric, handed a reprieve to enter the draw despite losing in qualifying to Mikhail Kukushkin, will face either Grigor Dimitrov or Dominic Thiem in Friday's quarter-finals.

Coric has now, though, beaten the Wimbledon champion in two of their four meetings having thrashed Murray at the Qatar Open at the Dubai Tennis Championships in 2015.

Murray was made to pay for missing break point opportunities early in both sets as Coric adjusted better to the indoor conditions with the roof at the Manolo Santana court closed due to rain.

Coric saved two break points to hold for 2-2 in the opening set before a run of three consecutive breaks of serve opened up a 4-3 lead for the 20-year-old.

And he rammed home his advantage by breaking the fragile Murray serve again to close out the set.

Murray had his chances once more with two more break points early in the second.

But after failing to capitalise the Scot looked distracted as he remonstrated with his coaching staff as the second set went with serve until a terrible eighth game from Murray gifted Coric the break once more.

Despite the pressure of serving for the match, Coric remained cool to seal victory in just under 90 minutes on court when Murray fired wide.

AFP