Ben Shelton had to come from behind to beat fellow American Marcos Giron and reach the Japan Open final in Tokyo.

The 21-year-old reached his maiden championship match in his debut year on the ATP Tour with a 6-7(2) 7-6(5) 6-4 win from a set and two breaks down.

Following his landmark victory, Shelton claimed it was one of the trickiest encounters he’d been involved in.

“It’s a huge achievement for me and my team,” Shelton said on court following the win. “Especially the way that the match panned out today.

“It’s definitely one of the toughest matches I’ve played in my life. Marcos was waxing me from the baseline at almost every rally and I had to completely change my game up to even have a chance to compete against him.

“To be able to get through that match and not only figure things out but get a win, going into my first ATP final, the win couldn’t be sweeter.”

From 5-2 behind in the second set, Shelton rallied to win four straight games and shift the momentum, pulling level with a second set point in the tie-break.

Giron made things easier for Shelton in the decider when he squandered three break points.

Shelton grabbed the chance with both hands to go 4-3 up and from there he was able to see the victory out on his first match point.

The American will play Aslan Karatsev in Sunday’s final after he overcame Shintaro Mochizuki in straight sets, 6-3 6-4.