Madrid: World number one Andy Murray`s slump in form continued as he crashed out of the Madrid Masters third round 6-3, 6-3 to lucky loser Borna Coric on Thursday.
Defending champion Novak Djokovic did ease into the quarter-finals, though, with a 6-4, 7-5 win over Feliciano Lopez.
Coric was only handed a late reprieve to enter the draw in Madrid after losing in qualifying to Mikhail Kukushkin.
"After one match of the quallies where I lost and I was booking my flight back to home," said Coric.
"I couldn`t imagine this when I woke up this morning, I always believed but I wasn`t sure how I was going to play.
"In the end I played as I had dreamed."
However, Murray cut a frustrated figure as he was swept aside by the 20-year-old Croatian for the second time in the pair`s four meetings.
"I didn`t help myself find a way into the match to start playing better," said Murray.
"I definitely think I need to be concerned about today.
"It`s not always the worst thing losing a match, but it`s sometimes the manner of how you lose the match is what can be concerning or disappointing."
Coric broke the fragile Murray serve three times in the first set under the roof at the Manolo Santana centre court due to rain in the Spanish capital.
And one poor service game from the Wimbledon champion cost him dear in the second as Coric served out for the match to set up a quarter-final meeting with Grigor Dimitrov or Dominic Thiem.
Djokovic has had his own struggles of late.
The Serb parted ways with his coaching staff of 10 years last week after also suffering early exits at the Australian Open and Monte Carlo Masters.
However, he believes he is making slow but steady progress after seeing off Lopez and a partisan crowd to reach the last eight.
"If you`re playing against a Spanish player in Madrid, it`s obviously a different game, it`s a different feeling," said Djokovic.
"They have a lot of support. You need to kind of hold your nerve, hold your concentration, and use all the necessary energy at the right moments."
Djokovic faces a much tougher test on Friday against world number eight Kei Nishikori, who earlier swept aside David Ferrer 6-4, 6-3.
However, Nishikori has only won two of their previous 13 meetings.
"Novak is someone that I don`t have good record (against)," said the Japanese.
"I got to stay really positive and I got to play great tennis to beat him. I try to enjoy my big challenge tomorrow."
Rafael Nadal`s quest for a third straight title after wins in Monte Carlo and Barcelona faces a stiff test against Nick Kyrgios in the night session.
David Goffin awaits the winner of that clash after the Belgian beat world number six Milos Raonic 6-4, 6-2.
Dominic Thiem saved five match points to edge out Grigor Dimitrov a thrilling third set tie-break 4-6, 6-4, 7-6 (11/9).
The Austrian will face 20-year-old German Alexander Zverev next after his fine form continued with a 6-4, 6-4 win over 11th seed Tomas Berdych.
In the women`s Madrid Open, third seed Simona Halep remains on course to defend her title as she thrashed American Coco Vandeweghe 6-1, 6-1.
Halep faces Latvian Anastasija Sevastova in Friday`s semi-finals after the world number 22 saw off Kiki Bertens 6-3, 6-3.
France`s Kristina Mladenovic also reached the last four in straight sets 6-4, 6-4 over Sorana Cristea.