MELBOURNE, Australia — It took five sets and nearly five hours, but Denis Istomin hung in there against the world’s No. 2 player, sending Novak Djokovic packing Thursday in the second round of the Australian Open.

Istomin, a bespectacled wild card from Uzbekistan who is ranked 117th in the world, knocked out Djokovic, 7-6 (10-8), 5-7, 2-6, 7-6 (7-5), 6-4. He is the only the fourth wild card in the Open era to beat a top-two seed and his postmatch remarks were full of self-aware humor.

“First of all, I feel sorry for Novak, I was playing so good today,” he joked as he addressed the crowd, adding with a laugh, “I mean, I surprised myself as well today.”

After dropping the first set, Djokovic was whistling “Don’t Worry, Be Happy,” a tune clearly at odds with what he was feeling. “I’m not used to losing in the Australian Open second round,” the defending champion said. “The last 10 years, I’ve won six titles here. It’s disappointing but I have to accept it.”

Djokovic double faulted nine times and had 72 unforced errors along with his 14 aces and 68 winners.

But Istomin was simply better, with three double faults, 17 aces, 61 unforced errors and 63 winners.

“All credit to Denis. He was a better player in the clutch moments. He stepped it up, played aggressive, served very well, very precise,” said Djokovic, who was replaced atop the world rankings by Andy Murray in November. “It’s a tennis match. On a given day you can lose. Nothing is impossible. There are over a hundred players in the main draw. The quality of tennis keeps rising each year. There was not much I could do. I was not pleased with my performance overall.”

Istomin credited Klaudiya Istomina, his mother and coach, for her work and encouragement after a broken leg threatened his career in 2001. “Thanks Mum,” he said, adding later, “When your family is part of your team, it’s great. I am lucky my mother is coaching me. The other good thing is I don’t need to pay the coach extra. After all these years together, we have a good relationship. We understand each other very well.”

The exit is Djokovic’s earliest in a Grand Slam since Wimbledon in 2008 and he is now 33-1 against players not ranked among the world’s top 100 in Grand Slam events. What, he was asked, does he take from the match.

“Take my bags and I go home.”

Also on Thursday:

 Rafael Nadal swept aside 2006 Australian Open finalist Marcos Baghdatis 6-3, 6-1, 6-3 to advance to the third round.

The 14-time major champion won on his third match point in 2 hours, 13 minutes.

 Serena Williams, playing on the same court that saw Djokovic lose, beat Lucie Safarova, 6-3, 6-4.

It was their first meeting since Williams won their French Open final in 2015.

 Croatian veteran Mirjana Lucic-Baroni beat third-seeded Agnieszka Radwanska 6-3, 6-2 to reach the third round – her best performance at the tournament in 19 years.

“It’s amazing. Oh my God, it’s been so long since I won a match or two. Well, this is the first time ever in Australia,” she said. “As I’m getting older, it seems I’m getting better.”

Lucic-Baroni, 34, won the 1998 Australian Open doubles title with Martina Hingis at the age of 15. She also made the 1999 Wimbledon singles semifinals before deciding to quit the sport for several years.

“I was a little baby back then,” she said of her early success. “Now I can be maybe more relaxed. I said to myself today on the court, don’t worry, be happy.”

 A TV commentator apologized for how he spoke about Venus Williams’ play, saying he was describing her aggressive style as “guerrilla” tactics and not comparing her to a “gorilla.”

Former tennis pro Doug Adler said he was speaking about Williams’ tactics and strategy and “simply and inadvertently chose the wrong word.”

Adler was doing play-by-play commentary on ESPN for Williams’ second-round match against Stefanie Voegele, saying Williams was playing more aggressively after Voegele missed serves. After Voegele faulted on a serve, Adler described Venus as moving in and charging with a “gorilla effect” or “guerrilla effect.”

The remark sparked quick reaction on Twitter, with some offended users calling for Adler to be fired for comparing Williams, who is African-American, with a gorilla.

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