France's Harold Mayot insists he is playing the best tennis of his career after booking a place in the 2019 ITF Junior Finals boys' title-decider by overcoming Shintaro Mochizuki of Japan in a crunch semi-final showdown.

With play once again transferred indoors due to heavy rainfall in Chengdu, Mayot cut a composed figure from the outset and dispatched reigning Wimbledon boys' champion Mochizuki 6-2 7-5.

Standing between Mayot and silverware is Denmark's Holger Vitus Nodskov Rune, who overcame France's Valentin Royer in another hotly-contested last-four Far East tussle.

Rune defeated Mayot in the round-robin phase of the competition, but after chalking up wins against the two top-ranked boys on the planet in Jonas Forejtek and now Mochizuki, Mayot believes he is on the crest of a significant wave.

"I think I am playing the best tennis of my career," Mayot told itftennis.com. "In beating Jonas and Shintaro, I overcame two players who have won Junior Grand Slams this year and those were my two best performances. 

"I work very hard with my coach [Thierry Tulasne] and I learn a lot from him. He is like my second father and I truly believe in him. We work very hard together and it's because of him that I play well." 

Mayot's victory also maintained the possibility of a French double, with Diane Parry reaching the final of the girls' draw earlier in the day following victory over compatriot Elsa Jacquemot.

Never in the history of the ITF Junior Finals has a nation provided both the boys' and girls' winners, while success for Mayot and Parry would also replicate the title-winning results of JA Osaka last weekend. 

"It has been amazing for us to have four French semi-finalists here," added Mayot. "I'm happy for Diane, who has made the final also. For the FFT, it would be amazing to have two French winners. 

"For now, though, I'm just happy to be in the final. Shintaro is a very good player and it's tough to play against him. He takes the ball so early but I think I managed the match very well. I just played my game and was very focused."

Rune, meanwhile, believes the world's best two junior players will do battle for the ITF Junior Finals crown on Centre Court at the Sichuan International Tennis Centre on Sunday.

The 16-year-old headed into the semi-final with question marks over his fitness having injured his left ankle during his final round-robin encounter against Forejtek.

He conducted a rigorous workout on the gym's treadmill during the morning and generally appeared to be moving freely during his 7-6(5) 4-6 6-2 triumph over Royer, during which he was required to recover from 5-2 down in the first set.

"Harold and I played against each other in the round-robin stage and it was close, but this is a fresh match," said Rune. "It will be a great final. I said after our match that I felt we are the best two junior players and, looking at the final, I was right.

"I'm very excited. Harold and I always have great battles. They are always close and I'm extremely excited to go out there and fight."

Not only are a trophy and prestige up for grabs, reigning Roland Garros champion Rune is also in contention to assume the junior world No. 1 ranking should he defeat Mayot, although that is not his overriding concern.

"It would mean a lot to be junior world No. 1 but I'm not thinking about it too much," he added. "I'm just determined to go out there and fight for every point and every game." 

Forejtek, meanwhile, secured fifth place at the tournament by overpowering Argentina's Thiago Agustin Tirante 6-3 7-5.