Cincinnati, OH, USA, 21 August 2017 | AAP

Nick Kyrgios went down in the Cincinnati Masters final to Grigor Dimitrov in straight sets on Sunday.

Kyrgios lost 6-3 7-5, the Australian unable to reproduce the form which saw him beat world No.1 Rafael Nadal in the quarterfinals.

Kyrgios capitulated with three double faults in the 11th game of the second set, handing Bulgarian Dimitrov a decisive break and a 6-5 lead.

“Looking back from where I was a couple weeks ago, I would have never thought I would have had my first Masters 1000 final,” Kyrgios reflected.

“So I’m pretty happy with the result. From where I was to being here, it’s just been amazing.

“I’m feeling good. I’m pretty excited for the US Open. I’m just happy, being out there and getting some wins again.”

World No.23 Kyrgios had the first break point of the match at 2-2 in the first set, but sent a forehand wide to miss the chance.

Dimitrov, however, took full advantage of his one break opportunity when Kyrgios netted a forehand to take a 4-2 lead.

The Australian had a chance to break back in the very next game, but a backhand error proved costly.

It was all world No. 11 Dimitrov required and he took the set to stamp his authority in the match.

Dimitrov did not lose a set on the way to winning his first ATP Masters tournament, with Kygrios in full praise of his opponent’s fitness.

“I was struggling a couple of weeks ago and he got me out on the practice court. We practised for an hour-and-a-half and I was struggling and he was fresh,” Kyrgios said.

“You had me mentally today already. I was like, ‘I know this guy’s fitter than me’.”

Kyrgios will next turn his attention to the US Open, beginning 28 August in New York.