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.

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.

And oh how he did it.

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.

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 looked anything but the champion after winning only one point in the first two games and dropping the opening set in just 29 minutes.

Seemingly hindered by a left arm soreness from his torrid campaign, he trailed three times by a break in the second set.

But once he nudged his way in front, there was no looking back as the youngster powered through the third set to prevail after one hours and 35 minutes.