Brisbane QLD, Australia, 1 January 2017 | AAP

Two Australian teens have stunned more credentialled opposition to take their places in the main draw at the Brisbane International.

Melbourne 16-year-old Destanee Aiava continuing a purple patch of form, taking little time to dispatch German world No.86 Carina Witthoeft 6-1 6-1 in her final qualifying match in 35-degree heat at the Queensland Tennis Centre on Sunday.

> READ MORE: Destanee’s the child for Aussie tennis

Later the same day, Spain-based Alex De Minaur ensured four Australian men will play in the main draw of the Brisbane International following an energy-sapping qualifying triumph.

De Minaur, who grew up in Sydney before moving overseas with his family, fought back on Sunday to overcome American Frances Tiafoe 6-7(4) 6-4 6-4 in two hours and 19 minutes in the sweltering conditions.

The 17-year-old joins Bernard Tomic, Sam Groth and Jordan Thompson in the main draw.

De Minaur was cheered on by Davis Cup captain Lleyton Hewitt out on court six; Hewitt has worked hard with the 17-year-old over the past two months and was highly impressed.

“I’m just rapt for Alex,” he said. “What a way to start the new year.

“He has a lot of ability, he wants to work hard (and) puts in a lot of hard hours … that’s the main reason he was able to win today.”

Aiava’s win over Witthoeft followed a 6-0 6-4 victory over Samantha Crawford – who reached the semis in Brisbane last year – in her first-round match, and a 6-2 6-0 defeat of Maria Jose Martinez Sanchez in round two.

Her maiden WTA main draw appearance, alongside Sam Stosur and Ash Barty, comes after winning a wildcard into this month’s Australian Open by taking out the Australian 18/u Championships last month.

Aiava will face fellow qualifier Bethanie Mattek-Sands in her opening round match.