“I have never really felt that I played my best tennis here,” he said. “I still feel like I can’t really go for my shots. I feel like when I do, I make mistakes long. I have tried many different things. I don’t know exactly why it is.”

Delbonis scored the biggest win of his career, outlasting the second-seeded Murray in a two-hour, 46-minute struggle. Three years ago, Delbonis defeated then-fifth-ranked Roger Federer in the semi-finals at Hamburg.

“With the crowd, it’s a little bit more pressure, but I’m enjoying that kind of matches,” Delbonis said. “It’s like a challenge every time, and I happy to get it.”

The left-handed Argentine rallied from 4-1 down in the third set, winning three straight games for a 4-all tie. He held serve to tie it 5-all and broke Murray in the next game to go up 6-5. Murray broke back to force the tiebreaker, but not without a fight by Delbonis, who trailed 15-40 and got to deuce before sending a backhand wide to let Murray even the set, 6-all.

“I just didn’t feel comfortable going for my serve,” said Murray, who had no aces and three double-faults. “I felt like every time I went for it I missed it. I didn’t have control on that shot at all.”

Murray led 3-2 in the breaker before Delbonis reeled off five straight points to close out the match, using his heavy topspin to change up the pace. Murray committed errors on the last three points, with his forehand landing wide on match point.

“I feel good on the surface because it’s not too fast,” Delbonis said. “I can slice in that kind of court. I like it. I like to play in that kind of court, in hard courts that are not so fast. For me it’s a good court to be aggressive.”

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Murray was competing in his first tournament as a father. His wife, Kim, gave birth to daughter Sophia on February 7, a week after the Scotsman finished as the runner-up to Novak Djokovic at the Australian Open.

“It will be nice to get to Miami and see my family,” said Murray, who next plays in the Miami tournament. “I do think I will play better tennis in Miami because I played some good stuff in the Davis Cup.”

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Murray is the highest seeded man to lose so far in the desert event.

Also advancing was No 8 seed Richard Gasquet, a 2-6, 6-2, 6-1 winner over Alexandr Dolgopolov and No 10 Marin Cilic, who beat Leonardo Mayer, 6-4, 6-3. No 12 seed Milos Raonic beat 17th-seeded Bernard Tomic 6-2, 3-0 after Tomic retired because of a wrist injury.

In women’s third-round matches, Swiss seventh seed Belinda Bencic was stunned by Slovakia’s Magdalena Rybarikova while former champion Ana Ivanovic was also sent packing in the third round of the BNP Paribas Open in California on Monday.

The 97th-ranked Rybarikova, who eliminated 31st seed Daria Gavrilova in her previous match, got by the powerful Bencic 6-4, 3-6, 6-3 while Czech Karolina Pliskova dumped former Serbian world number one Ivanovic 6-2, 6-0 in 49 minutes.

After an uneven start at the Indian Wells Tennis Garden, 18th seed Pliskova’s game clicked into gear in spectacular fashion, reeling off 10 consecutive games to close out her one-sided victory.

Ivanovic entered the tournament fresh off a run to the quarter-finals and semi-finals in Dubai and St. Petersburg, respectively, while Pliskova had suffered a couple of early exits in the Middle East.

Pliskova, perhaps, perked up in seeing Ivanovic across the net. She had won all three of her previous encounters with Ivanovic, including earlier this year in Sydney.

“We’ve played a few times already and I’ve always won. But I think I played really good tennis today and I’m happy that I made (the next round) so fast,” said Pliskova, who powered in 18 winners.

Next up for Pliskova will be Britain’s Johanna Konta, who advanced 6-4, 6-1 over Czech Denisa Allertova, who had conquered second-seeded Australian Open champion Angelique Kerber in the previous round.

Rybarikova advanced to another challenging test against US Open runner-up Roberta Vinci.

The ninth-seeded Italian hurried past Elina Svitolina of Ukraine 6-1, 6-3 to book her spot in the fourth round.

Russian Daria Kasatkina defeated Puerto Rican Monica Puig 6-4, 3-6, 7-6 (7-2). Kasatkina’s fourth round opponent will be Swiss Timea Bacsinszky. The 12th seed overcame Canadian Eugenie Bouchard 6-2, 7-5, 6-2.

Australian Samantha Stosur advanced past American Christina McHale 6-4 2-6 6-4. Stosur will meet the winner of the final third-round match between China’s Shuai Zhang and 13th seed Victoria Azarenka of Belarus.

Associated Press, Reuters