NEW YORK (AP) -Juan Martin del Potro's gliding under the radar at the U.S. Open is about to end.
Del Potro will make his first appearance in Arthur Ashe Stadium on Wednesday when he faces sixth-ranked Andy Murray in the first quarterfinal for both players at this Grand Slam.
Until late Monday, the second hottest player on the men's tour had been beating opponents away from the big showcourt lights given to Rafael Nadal, Roger Federer, Novak Djokovic and Americans.
No problem. The 6-foot-6 (1.98-meter) Argentine teenager struck down Guillermo Canas, Thomaz Bellucci and Gilles Simon before ousting Kei Nishikori in Louis Armstrong Stadium to extend his winning streak to 23 matches.
The streak is the longest by anyone outside the top 10 in the last 20 years, and second this year to only Nadal's 32 straight wins.
How's he handling it, three weeks before he turns 20? He's not even thinking about it, he says.
"I don't think about other tournaments or other matches," del Potro says. "I just think in the moment about what I'm doing, and that's it."
What he's done is become the first teenager since 2001 to reach the U.S. Open quarterfinals, and lift his ranking from No. 50 at the start of the year to guaranteed top 15, for now.
Del Potro's run began in mid-July at Stuttgart, where he earned his first ATP title. The following week he won in Kitzbuhel, beating hometown favorite Jurgen Melzer. Then he upset Andy Roddick to win Los Angeles, and become the first Argentine to claim an American hard-court title since Guillermo Vilas in 1977.
The next week del Potro won at Washington, becoming the first player in the Open era to win the first four titles of his career, in succession. To no surprise, he cited exhaustion in withdrawing from the New Haven tournament in the week before the U.S. Open.
After starting playing tennis at age 7 in Tandil, an inland city visited by adventure-seekers, del Potro dreamed of winning his first ATP title, a Grand Slam and the Davis Cup. He has an ATP title, he's into his first Grand Slam quarters, and he's back in Argentina's team for this month's Davis Cup semifinals.
His career looked in jeopardy for a while this year with back problems, but he overcame them with improved fitness and a new coach. His serve cranked up and he's been unstoppable for two months.
"It's really crazy to be here in the quarterfinals but with all that's gone on in the last few weeks it seems normal," del Potro says. "It's hard to realize what I've done."