BRISBANE (REUTERS) - American qualifier Samantha Crawford continued her breakout run at the Brisbane International by storming into her first WTA semi-final after pummelling Andrea Petkovic on Thursday.

The 20-year-old Atlanta native, ranked 142nd in the world, blasted 22 winners against the befuddled German in a 6-3, 6-0 rout to further enhance her reputation, although the former US Open junior champion was surprised about her achievement.

"It happened fast. I was trying to not think about it too much, not psych myself out," Crawford said. "Right after I won, on the on-court interview I was like shaking, and then in the locker room I was like sitting for just like a little bit.

"But yeah, this is awesome."

Crawford is playing in just her sixth WTA Tour event and her strong showing at an event which has seen the top seeds succumb to injuries should bring her inside the top 100 for the first time.

The American, who spent time growing up in China and speaks fluent Mandarin, has yet to drop a set in Brisbane after dispatching another rising talent Belinda Bencic of Switzerland in the second round.

She faces either twice Australian Open champion Victoria Azarenka or US Open finalist Roberta Vinci for a place in the final.

Germany's Angelique Kerber also booked a semi-final spot in Brisbane as she beat Russia's Anastasia Pavlyuchenko 6-4, 6-4.

At No. 4, the German is the best ranked seed remaining after injury robbed the tournament of Maria Sharapova, Simona Halep and Garbine Muguruza.