Flat Kei Nishikori Hits Wall at Australian Open

Kei Nishikori hit the wall at the Australian Open on Wednesday, deflating his devoted Japanese supporters as he was roughed up by Stan Wawrinka in the quarter-finals.

The Swiss defending champion had too many big guns for the fifth seed, rattling off a 6-3, 6-4, 7-6 (8/6) win in just over two hours on Rod Laver Arena. (Match report)

It means Wawrinka stays in the tournament with a semi-final against either Novak Djokovic or Milos Raonic beckoning, while Nishikori exits after falling at his first big hurdle at Melbourne Park.

Much had been expected from the Florida-based 25-year-old after he beat Raonic, Wawrinka and Djokovic to reach the US Open final last September.

But apart from Wawrinka's nervous fluttering away of five match points in the third set tiebreaker, it was all one-way traffic.

"I felt a little bit tired, heavy. But mentally I was fine and I was ready to go. But he was a little better today," Nishikori conceded.

"I may have felt a little bit of pressure. But he was serving really well today because I usually return well and break in a couple games.

"So it was tough to find my game today and he was playing really aggressive, great forehand, backhand."

It was a far cry from the last time the pair met in the quarter-finals at the US Open when he won in five sets.

This time he coughed up three service breaks, made more errors than winners, 31-23, and lost the majority of the longer rallies, usually his bread and butter.

"I didn't start well. First couple of games I was missing so much, so many unforced errors. I was going for too much," he said.

"I don't know. I may have felt a little bit pressure."

Now that he is the hunted at world number five rather than the hunter, Nishikori said he is feeling more heat.

"Everybody is going to be tough from now because everybody is coming over 100 percent," he said.

"Even first couple matches I had here was really tough. Obviously they're going to put in 100 percent from the beginning."

Despite the defeat, Nishikori was overall happy with his 10 days' work at the year's first Grand Slam tournament.

"It wasn't really a bad week. It's not easy come quarter-final time at the Grand Slams," he said.

"I have to keep doing this. I could be better. But I need more of these experiences, playing tough all the time, playing a lot of matches. Especially in Grand Slam, there is more pressure."