LOS ANGELES — Lanky teenager Juan Martin del Potro rolled to a 6-1, 7-6(2) victory over Andy Roddick in the Countrywide Classic today to win his third championship in less than a month.

Running his match victory string to 14 in a row, the 19-year-old Argentine broke Roddick's serve three times in the first set and did not allow a break in the match.

Roddick, who had not lost his serve in 24 games heading into the final, recovered to hold serve in the second set, but del Potro won the final five points of the tiebreaker.

After Roddick's final shot of the match sailed out, del Potro grinned, raised his arms then flopped on his back onto the court. A group of young fans in the stands waved an Argentine flag and cheered.

The 6-foot-6 del Potro controlled the match with powerful, pinpoint ground strokes, consistently hitting hard forehands just inside the lines.

The title was his first in a hardcourt tournament. He had captured his first career ATP title by upsetting Richard Gasquet in Munich on July 13, then beat Jurgen Melzer to win the following week in Kitzbuehel, Austria. Both those tournaments were on clay.

The victory over the 25-year-old Roddick, the former No. 1 who is ranked ninth, was the biggest so far for the del Potro, who has moved up to No. 24 and will vault into the top 20. He came into the final at UCLA with a 1-13 record against top 10 opponents, with the lone win coming against No. 9 Tommy Robredo last October.

Del Potro became the first teenager to win the Los Angeles tournament since Pete Sampras did it as a 19-year-old in 1991.