Kei Nishikori lamented being pushed to five sets by Andrey Kuznetsov in a first-round scare at the Australian Open.
The Japanese fifth seed was challenged before edging past Kuznetsov 5-7 6-1 6-4 6-7 (6-8) 6-2 in hot conditions at Melbourne Park on Monday.
Nishikori needed three hours, 34 minutes to advance and the 2014 US Open runner-up believes he should have completed the job more easily.
"I think I let him come back in the fourth set. I should have finished that set," he said.
"I was up in the tie-break, but I think he played well from the beginning.
"Fifth set I started playing much better. It was tough, a really tough match."
Nishikori confirmed he will not play in Japan's Davis Cup tie against France, which takes place in Tokyo the week after the Australian Open.
"I'm not playing because the schedule, it's gonna be too tight," he explained. "Going [to] South America, Rio and Buenos Aires, and if I play Davis Cup, that's way too much, you know, for my body. And Indian Wells and Miami is coming up after. So I just decided not to play.
"I hope they can make some changes. Right now I think it's way too much to play three times [a year in the Davis Cup] or even if you play the final, maybe four, I think.
"I think that has to change, for sure, to make it shorter. I think all the players - I don't know if all, but I think most of them are hoping for change."
Awaiting Nishikori in the second round is Jeremy Chardy, the Frenchman who was on court for just 23 minutes and led Nicolas Almagro 4-0 before the Spaniard retired.