Houston (USA):American teen Ryan Harrison became the third-youngest player in 18 years to win an ATP match, defeating Pablo Cuevas of Uruguay 6-4, 6-3, at the ATP US Men's Clay Court Championship.
Harrison, 15, became the 10th player in the Open Era on Monday to win an ATP match at such a young age.
He joins Richard Gasquet and world number 2 Rafael Nadal as the only 15-year-olds to win a match since 1990.
Ranked 1,277 in the world, Harrison could face top-seeded James Blake in the next round.
American Blake is hoping to carry the momentum from his Davis Cup victories over the ATP Tour.
Blake captured a pair of singles wins in the US' 4-1 victory over France in the Davis Cup quarter-finals over the weekend.
Clay has been a difficult surface for the American, although Blake did show some signs of improvement with an appearance in the semifinal here last year.
However, it did not translate over to the French Open, as the 28-year-old fell to Ivo Karlovic in the first round.
The second seed is Germany's Tommy Haas, who won this event in 2004.
Haas also will begin play later in the week, squaring off against Russia's Igor Kunitsyn.
Karlovic, the defending champion, is not entered in the draw.
In all, there are 11 Americans entered, including third seed Mardy Fish and fourth-seeded Sam Querrey. Both players will start first-round play later.
Rising star Donald Young posted a 6-3, 7-6 (7/5) victory over Spanish qualifier Fernando Vicente yesterday.