Cincinnati, OH, USA, 15 August 2018 | AAP/tennis.com.au

Nick Kyrgios overcame the embarrassment of forgetting his tennis shoes to battle into the second round of the Cincinnati Open with a three-set victory over American qualifier Denis Kudla.

Fellow Australian Ash Barty has no such trouble, shutting out Czech wildcard Marketa Vondrousova in straight sets.

Kyrgios, the Australian men’s No.1, held up the start of play as he was seen searching his kit bag on court before admitting to officials he hadn’t packed his trainers.

“Wait, what?” Kyrgios could be heard saying on camera as he went through the various compartments of his tennis bag before realising what had happened.

After walking around the side of the court in his dark grey socks to find someone who could retrieve his shoes, the embarrassed world No.18 then told his bemused opponent: “I left my tennis shoes in the locker room, sorry man.”

But after a tournament aide came to the rescue by retrieving his required footwear from the locker room, which meant he didn’t have to play in the basketball shoes he walked on to court in, last year’s tournament runner-up wrapped up a nervy 6-7(2) 7-5 7-6(7) victory.

The mercurial Kyrgios again produced some dazzling shots and also fired 39 aces, including a huge second-serve ace when down at match point as he saw off his battling opponent, who was fresh off reaching the quarterfinals in Washington DC.

Rule No. 1⃣

Expect the unexpected from @NickKyrgios 😏#CincyTennis pic.twitter.com/qYxt21ocnd

— Tennis TV (@TennisTV) August 14, 2018

Despite his win, there were concerns for Kygrios, who showed signs of being troubled by injury as he secured a showdown with Croatian Borna Coric, a 6-2 6-3 winner over Russian qualifier Daniil Medvedev.

Kyrgios last year reached the final in Cincinnati.

Barty, meanwhile, posted a 6-3 7-5 victory over dangerous lefty Vondrousova,

She trailed 5-3 in the second set and saved a set point in the ninth game before winning four straight games to wrap up victory in an hour and a half.

The Queenslander, who reached the semifinals at last week’s WTA tournament in Montreal, next faces qualifier Kaia Kanepi, a former world No.15.

Simona Halep, the world No.1 who beat Barty in the last four in Montreal, looms as a third-round opponent.

But first, Halep must get past another Aussie in qualifier Ajla Tomljanovic, who on Monday advanced to the second round with victory over Irina-Camelia Begu.