New York - Japanese seventh seed Kei Nishikori spoke of his growing confidence Wednesday after advancing to the US Open third round following a gritty 6-2, 4-6, 6-3, 7-5 win over American Bradley Klahn.
Steady rain restricted play to the two main show courts to start the day at Flushing Meadows, where Nishikori, the 2014 runner-up, needed five match points to eventually oust 108th-ranked Klahn.
"I think today's match will help. There were some up-and-downs and I think I needed to play a lot of tennis, especially because I lost two first rounds, Cincy and Canada," said Nishikori, who arrived in New York without a hardcourt win since Indian Wells in March.
"I needed to have little more confidence. So I think it was good match today. But before coming into here, I was a little bit worried, of course. I didn't have much confidence, but I think now it's getting bigger and more confidence is coming into my head."
Nishikori has reached the quarter-finals or better at the last five Grand Slam tournaments and will take on either Chilean 31st seed Cristian Garin or Australia's Alex de Minaur for a spot in the last 16.
However, he was made to scrap against Klahn under the roof at Louis Armstrong Stadium after surrendering a 5-1 cushion in the final set.
"I knew it was going to be a tough one because he has a great serve," said Nishikori, a semi-finalist on his last two appearances at Flushing Meadows.
"A little bit of lost focus. After 5-1, I was serving for the match at 5-2 and he started playing better too. I'm happy to win of course, it was a good match and I'm looking forward to playing the next one.
"Overall I think played good tennis. Some of the moments I think I didn't play well," he added.
Nishikori spent just 47 minutes on court in the first round Monday as Argentine qualifier Marco Trungelliti quit with a back injury midway through the second set.
He said the protracted finish to his win over Klahn was not necessarily a bad thing.
"I think always there is positives side if you play a long match," he said.
"Of course it's better to win straight sets in one or two hours. Yeah, today I learned couple things. Yeah, sometimes it's good to have lots of tennis on the court and especially first couple rounds."
US Open results on Wednesday (x denotes seeding):
Roger Federer (SUI x3) bt Damir Dzumhur (BIH) 3-6, 6-2, 6-3, 6-4
Grigor Dimitrov (BUL) bt Borna Coric (CRO x12) walkover
Kei Nishikori (JPN x7) bt Bradley Klahn (USA) 6-2, 4-6, 6-3, 7-5
Elina Svitolina (UKR x5) bt Venus Williams (USA) 6-4, 6-4
Karolina Pliskova (CZE x3) bt Mariam Bolkvadze (GEO) 6-1, 6-4