MADRID (AP) -- Andy Murray's struggles continued with a 6-3, 6-3 loss to lucky loser Borna Coric in the third round of the Madrid Open on Thursday, while defending champion Novak Djokovic made it to the quarterfinals by defeating Spanish veteran Feliciano Lopez 6-4, 7-5.
The top-ranked Murray was outplayed by the 20-year-old Croatian to lose his fifth match of the year.
He has won only one tournament this season and hasn't made it past the semifinals in the three clay-court tournaments he has played.
The 59th-ranked Coric became the first lucky loser to reach the quarterfinals in Madrid. He only made it to the main draw after Richard Gasquet withdrew because of a back injury.
Coric will try to win his second tournament this season. He won his first career title in Marrakech, Morocco last month.
Murray, who lost last year's final to Djokovic in Madrid, had 28 unforced errors in a disappointing outing under the closed roof of the center court in Madrid. He was broken three consecutive times in the first set, and once in the second to give Coric a 5-3 lead that the young Croatian converted to close out the match in less than an hour in a half.
Murray won his only title of the year in Dubai and had started the clay season trying to regain his form following a right elbow injury that kept him out of the Miami Open and the Davis Cup quarterfinals. He lost to Albert Ramos-Vinolas in the third round in Monte Carlo after blowing a 4-0 lead in the deciding set, then was eliminated by Dominic Thiem in the semifinals of the Barcelona Open.
Second-ranked Djokovic has also struggled this season but stayed alive in Madrid with the two-set victory over Lopez.
The Serbian was in control during his service games and broke Lopez once in each set to secure the victory. He saved the only break point he conceded to Lopez, who was playing in the tournament for a record 16th time.
"The level was definitely very high today I thought from both players," Djokovic said. "I think Feliciano played really well, especially in the second set. I wasn't winning too many points on his service games until the last one where I managed to return many balls back in play and then win the match."
Djokovic won in Doha to start the year but never made it past the quarterfinals in the following four tournaments he played since then.
He will next play against sixth-seeded Kei Nishikori of Japan, who defeated David Ferrer 6-4, 6-3 to deny the Spaniard his 700th career win.
A finalist in Madrid in 2014, Nishikori is playing in his first tournament since March. He withdrew from Barcelona last month because of a right wrist injury.
Ninth-seeded David Goffin of Belgium cruised to a 6-4, 6-2 win over fifth-seeded Milos Raonic of Canada and will play the quarterfinal against either Nick Kyrgios of Australia or four-time Madrid champion Rafael Nadal.
On the women's side, third-seeded Simona Halep of Romania reached the semifinals by beating Coco Vandeweghe of the U.S. 6-1, 6-1. She will play Anastasija Sevastova of Latvia, who defeated Kiki Bertens of the Netherlands 6-3, 6-3.
Kristina Mladenovic of France advanced to the final four by beating Sorana Cirstea of Romania 6-4, 6-4. She will play either Canadian Eugenie Bouchard or eighth-seeded Svetlana Kuznetsova of Russia.