"That was pretty cool," an elated Brandon Nakashima said after signing a plethora of autographs for his new legion of fans in Chengdu.

The American teenager will have to keep practising his signature if his form this week at the Sichuan International Tennis Centre is anything to go by.

A clinical display dispatched world No. 1 Chun Hsin Tseng 6-2 6-1 to lift the 2018 ITF Junior Masters boys trophy.

"I feel great. I'm so proud of the way I played today. It's been a long week, with a lot of great players and I'm so happy to come out on top. It's definitely the highlight of my year."

Tseng arrived on court as the heavy favourite, with two Grand Slams to his name in 2018, alongside an unbeaten record in four matches in Chengdu this week.

However, Nakashima defied his ranking of No. 13 to top his round robin group and put in a devastating performance to topple the top seed inside an hour.

Nakashima stepped in and attacked on return to assert his authority. From 2-2 in the first set, the American's relentless consistency and piercing accuracy into the corners chalked up six consecutive games onto the scoreboard to launch 6-2 2-0 into the lead.

"I just tried to stay solid on my side of the net, to make sure I cut down the mistakes and play every point with high intensity," said Nakashima, revealing the secrets to his success.

"I try to stay as calm and composed as possible during the match, without showing too much emotion. I think that is a real asset for me."

Tseng finally found his radar and broke with fine combinations, but that was a minor blip in Nakashima's dominant display.

The world No. 13 catapulted two return winners, one off each groundstroke wing, to post 3-1 as Nakashima dismissed any glimpse of a comeback to collect the trophy.

"I love this event and the city, it just feels great. I had a really good time here," added the San Diego resident after a memorable trip to China.

"It will give me a lot of confidence heading into my next tournaments and next season."

Meanwhile, Tseng had to settle for silver, but the Chinese Taipei teenager admitted he was outplayed on the day.

"Brandon was just too good today. He served and returned really deep, so I didn't have a lot of chances to get into the rallies or control many points," said a forward-thinking Tseng following his last junior tournament.

"I'm very sad, but this has still been a great experience and I've learnt a lot here to help me get better in the future."

"It can be good to lose sometimes as it makes it obvious what you need to improve on."

Adrian Andreev claimed third place in the final standings. The Bulgarian was leading Youth Olympic Games gold medallist Hugo Gaston 6-3 4-2 when the Frenchman was forced to retire injured.

"I'm pretty happy to pass today, I think it was a great experience to play a final match here today. Now it is time to rest," reflected the 17-year-old, who is inspired by his trip to Chengdu to keep on progressing.

"It's been a very, very helpful experience for me to realise that our level is the same. We want to reach the same goals, I think everyone here plays pretty much the same level. Everyone can beat anyone, it's just some players have been more consistent reaching that level.

"It's a good thing to see you still need to improve physically and mentally. I need to try and improve everything every day, to work as hard as I possibly can. Then hopefully I can reach my dreams and goals."

Finally, Italy's Lorenzo Musetti posted a 6-4 6-1 victory over Colombian charge Nicolas Mejia to finish fifth place in the standings.