Top seed Bartram defeated compatriot Dahnon Ward 6-4, 6-1 to take the boys' title while the unseeded Moreira Lanai got the better of Japan's Yuma Takamuro in a thrilling 7-5, 2-6, 7-6 victory in the girls' final.

"It's just an amazing feeling to know that I'll always be the first winner. It's just a great feeling," Bartram said after the win.

"It's different from any tournament that I've ever been to. It's just an amazing atmosphere. It's just the best facilities. It's just been amazing."

The dramatic girls' final finished in 2 hours and three minutes in the Brazilian’s favour.

Moreira Lanai saved two match points at 6-5 in the final set before registering a 10-point win in the tie break.

"What a fight, what a day for me," Moreira Lanai said.

"I'm very happy to be here in the US Open.

"These days, this final, this title, it's a dream come true to me.

"It's really special and big moment for me and my country.

"It's a dream for me because I always followed this tournament, always saw [it].

"Now, I'm champion here.

"I really enjoy these days.

"I'm really happy to be here. It's amazing."

The duo also won the doubles titles to add to their glory.

Bartram and Ward eased past Saalim Naser and Ivar van Rijt 6-4, 6-3 in the boys' final while Moreira Lanai and American Maylee Phelps demolished Ruby Bishop and Lily Lautenschlager 6-0, 6-0 in the other doubles final.

The US Open is the first Grand Slam to introduce a junior wheelchair tennis competition.