Shelton reaches first final at Japan Open

Rising American star Ben Shelton said he had to "shake things up" to reach his first ATP Tour final at the Japan Open on Saturday after another grueling three-set match.

The 21-year-old beat American qualifier Marcos Giron 6-7 (2/7), 7-6 (7/5), 6-4 in Tokyo and will face Russia's Aslan Karatsev in Sunday's final.

Shelton lost the first set and found himself two breaks down in the second against world number 79 Giron, who eliminated second seed Casper Ruud earlier this week.

Shelton said it was "definitely a difficult place to be in" and credited a change in strategy for turning the match in his favour.

"I knew that if I continued to keep playing the way I was, with the rhythm that he'd found, I was going to lose the match," he said.

"I tried to shake things up and try something that was going to surprise him.

"I was able to get him out of his rhythm for the three or four games that I needed to get myself back into the match."

Shelton rode the momentum after he had survived his second-set scare, closing out the match with an ace before letting out a roar and thumping his chest.

He said the encounter was "one of the tougher matches that I've played in my career".

"I definitely had to adjust during the match today and problem-solve and come up with solutions when my back was against the wall," he said.

"I was able to figure it out and get it done in three sets, but definitely not an easy task today."

US OPEN REMATCH

It was Shelton's third three-set match this week, with all of them featuring at least one tiebreaker.

Karatsev has won all his matches in straight sets, including his 6-3, 6-4 semifinal victory over Japanese wild card Shintaro Mochizuki.

Shelton said his route to the final had been "a little bit different".

"To be able to have been as composed as I was throughout the week, to get to the place that I'm in, I couldn't be happier," he said.

Karatsev has beaten fourth seed Alex de Minaur and sixth seed Frances Tiafoe this week in Tokyo.

He said his win over Mochizuki was "tricky", with the crowd getting behind the world number 215 home favourite after his unliklely run to the semifinals.

"The opponent was really hard, playing without any pressure," Karatsev said of 20-year-old Mochizuki, who knocked out top seed Taylor Fritz in the second round.

"I had to focus a little bit more than normal – if you lose the focus then the crowd can get crazy and then you're in trouble."

Karatsev lost to Shelton at the US Open, where the American reached the semifinals.

Karatsev said his opponent's long matches this week in Tokyo are unlikely to make much of a difference when they meet again in the final.

"I think he's really fit – it doesn't really matter whether he plays three sets or two sets," said Karatsev.

"Maybe I will come a little bit fresher than him, but I don't think it's a huge advantage."

SEMIFINALS RESULTS:

Aslan Karatsev (RUS) bt Shintaro Mochizuki (JPN) 6-3, 6-4

Ben Shelton (USA) bt Marcos Giron (USA) 6-7 (2/7), 7-6 (7/5), 6-4