Australian Open: Kei Nishikori claims straight sets win, advances to fourth round

Melbourne: Kei Nishikori was delighted with a straight-sets win Saturday, after two previous five-set battles, as he raced through the third round of the Australian Open to complete a Japanese double.

The in-form eighth seed felt his way into the first set against Portugal's 44th-ranked Joao Sousa before romping away to a 7-6 (8/6), 6-1, 6-2 win in 2hr 6min.

He was preceded onto Margaret Court Arena by countrywoman and US Open champion Naomi Osaka, who fought back from a set down to battle past Taiwan's Hsieh Su-wei.

The 29-year-old Nishikori has won all three of his first week matches on the same Melbourne Park second show court to reach the last 16 of the Australian Open for the seventh time in nine appearances.

"I love to play this court, I'm very comfortable here," said the 2014 US Open finalist after delighting a large contingent of Japanese fans.

"It's great to play here, especially after Naomi today."

Nishikori and Sousa had each survived two five-set epics before their third-round clash.

It looked odds-on for another marathon when they went shot-for-shot in the first set which Nishikori edged in a tiebreak after almost an hour.

But as the temperature began to rise in the mid-afternoon sunshine, Nishikori clearly decided he didn't want to go the distance again.

He agreed that managing to get back to the locker room after three sets for a change was useful going into the second week of a long tournament.

"Well, I think today will help," said the world number nine. "It was still tough, many long rallies. He was playing well, too. It wasn't an easy match.

"I should be okay. I try to recover well. I think that's the most important thing going into the second week. I hope I can recover well."

The last two sets flew by as Nishikori stepped on the gas, powering 19 unerring winners on his deadly forehand as he took just over an hour more to race through.

"The forehand is always my favourite shot," said Nishikori, who won the Brisbane International warm-up event and has extended his 2019 unbeaten run to seven matches.

"It's not just the forehand, everything was working well today," added the Japanese star, who will play 23rd seed Pablo Carreno Busta for a place in the quarter-finals.

Nishikori is steeling himself for a possible attritional battle against the Spanish baseliner.

"I'm sure it's going to be something like today. There is going to be many rallies. He's very solid from the baseline," he said of his fourth-round opponent.

"He can move well, good serve. I'm sure it's going to be a tough match."