MELBOURNE, Australia (AP) — Kei Nishikori could joke about it later, saying he faced more aces in one match from Ivo Karlovic than he himself would serve in a year.
Eighth-seeded Nishikori withstood 59 aces from Karlovic, and had to save three break points in a crucial 10th game of the fifth set, before beating the 39-year-old Croatian 6-3, 7-6 (6), 5-7, 5-7, 7-6 (7) to reach the third round of the Australian Open.
The 2014 U.S. Open finalist dropped to his hands and knees after the tiebreaker, relieved to secure his spot.
He hasn't made it easy on himself at Melbourne Park, having to come back from 0-2 down to win his opening match in five sets. He won the first two against Karlovic, but dropped the 11th games of the third and fourth sets and was taken again to a fifth.
"I was down love-40. He almost had it," the 29-year-old Japanese player said. "One serve and it could have gone his way."
Of course, he was asked about the aces — Karlovic had 59 aces and 98 unreturned serves; Nishikori had 9 aces.
"That's almost my one-year aces," Nishikori joked. "Never easy. Kind of frustrating if you can't get the serve like three in a row."
To force a fifth, Karlovic, who is 2.11 meters (6 foot, 11 inches) tall, had served six aces in a row. Two from 30-30 in the 10th game and then another four to close after breaking Nishikori's serve to close out the fourth set.
After trailing 4-1 in the 10-point tiebreaker — a new addition at the Australian Open this year __ and then taking a 7-6 lead thanks to a video replay review at 6-6 — Karlovic was closing in becoming the oldest man since Ken Rosewall in 1978 to reach the third round at the Australian Open.
But Nishikori stepped it up, winning the last three points and sparking chants of "Nishi-kori, Nishi-kori" from a section of Japanese fans at Margaret Court Arena.
"I had to reload in the fifth," he said. "It was really tough. Could go both ways. I was down 7-6 in the tiebreak. I really returned well — focussed well the last couple of points.
"We both played great tennis — and he served really well. I'll try to carry on this confidence to the next round."
After missing last year's Australian Open because of injury, Nishikori made the fourth round at the French Open, the quarterfinals at Wimbledon and the semifinals in New York. He's hoping to go a round further this time.
Rain showers halted play on all courts soon after Nishikori's win, forcing organizers to close the roofs of the three main show courts.
Earlier, Karolina Pliskova extended her winning start to the season after a rain-interrupted 4-6, 6-1, 6-0 win over Madison Brengle.
The 2016 U.S. Open finalist started this year with a run to the title at the Brisbane International.
After dropping serve twice in the first set against Brengle, Pliskova completely dominated the second and third sets and capped it with a pair of aces.
"Some breaks, some good tennis, and some bad mistakes from me too," Pliskova said.
She'll next play No. 27 Camila Giorgi, who beat Iga Swiatek 6-2, 6-0.
Madison Keys, the 2017 U.S. Open finalist, had a 6-3, 6-4 win over Anastasia Potapova to set up a third-round match against No. 12-seeded Elise Mertens, who beat Margarita Gasparyan 6-1, 7-5.
Keys has reached the semifinals in three of the last five majors and is gaining in confidence in Australia.
WTA Finals winner Elina Svitolina beat Viktoria Kuzmova 6-4, 6-1 in 67 minutes, No. 13 Anastasija Sevastova beat teenage Canadian qualifier Bianca Andreescu 6-3, 3-6, 6-2 and No. 21 Wang Qiang Wang had a 6-2, 6-3 win over Aleksandra Krunic.
Hsieh Su-wei advanced 6-3, 6-4 over Laura Siegemund, who had beaten two-time champion Victoria Azarenka in the first round.
Top-ranked Simona Halep was playing Sofia Kenin later Thursday, and seven-time Australian Open champion Serena Williams was set to meet Eugenie Bouchard in a night match.
Top-seeded Novak Djokovic, a six-time Australian titlist, was playing Jo-Wilfried Tsonga in a rematch of the 2008 final in the last match on Rod Laver Arena.
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