Kyrgios goes down in Masters final debut

A frustrated Nick Kyrgios has lost the Cincinnati Masters final to Grigor Dimitrov in straight-sets.

Kyrgios went down 6-3 7-5 on Sunday, with the Australian unable to maintain the form which saw him beat world No.1 Rafael Nadal in the quarter-finals.

Kyrgios capitulated with three double faults in the second set at 5-5 to hand Bulgarian Dimitrov a decisive break.

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 blow the chance.

HAPPY DAYS: Kyrgios and Dimitrov trade jokes in hilarious and classy speeches

NOT HAPPY: Kyrgios blows up at chair umpire

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.

Kyrgios remonstrated with the chair umpire during the second set, expressing anger with line umpiring.

"I know everyone makes mistakes, but come on, man," Kygrios told the umpire.

Kyrgios hit 15 aces to six but was weaker on serve throughout, winning only 36 per cent of points on his second-serve in the second-set.

He was forced to twice save break points in the second set at 3-3.

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 August 28 in New York.