New York, NY, USA, 8 September 2014 | AAP

Australian teenage tennis ace Omar Jasika has scored a mighty comeback win to complete a rare and spectacular US Open double in New York.

Jasika roared back from the dead to upset French fifth seed Quentin Halys 2-6 7-5 6-1 to become the first player in 28 years to win both the boys’ singles and doubles crowns at Flushing Meadows.

> NEWS: Jasika captures US Open boys’ doubles title

The 17-year-old from Melbourne joined countrymen Pat Cash (1982) and Bernard Tomic (2009) along with US Open men’s champions Stefan Edberg (1983), Andy Roddick (2000) and Andy Murray (2004) on the junior singles honour roll.

“It hasn’t really kicked in yet, but it feels unbelievable, like very honoured to be on one of the lists,” Jasika said.

“Yeah, just happy, very happy.”

Jasika looked completely gone after coughing up two horrible double-faults to fall behind 5-4 in the second set before producing an incredible fightback on Show Court 17.

Halys, the reigning European champion and world’s fourth-ranked junior, missed his chance to serve out the match as Jasika reeled off six straight games.

During one crazy spell, the Victorian left-hander won 17 out of 18 points from 4-5 down to 3-0 up in the deciding set.

“I just stuck in there, I guess,” Jasika said.

“This week has been unreal for me. Just sticking in and hanging in got me through a few matches, so I kept it in my head and I hung in and kept fighting.”

The victory completes a remarkable unbeaten 11-match campaign in New York for Jasika, who teamed with Japan’s Naoki Nakagawa to win the boys’ doubles title on Saturday.

For five straight days, the teenager had to play both singles and doubles but, unlike many others, he refused to yield in the intense heat and humidity.

Jasika admitted he started thinking about completing the double after upstaging highly-rated American Jared Donaldson – who was awarded a wildcard into the main draw and won 10 games off Gael Monfils – in the second round.

“I started to think about it in the back of my head,” he said.

“Imagine if I actually won singles and doubles. As I got closer, started to get into my head, all I was thinking was singles and doubles, singles and doubles – winning those two.

“I was actually very happy.”