Andy Roddick of the United States has advanced to the semi-finals of the U.S. Open tennis tournament in New York by overpowering 15th seeded Lleyton Hewitt of Australia 6-3, 7-5, 6-4 in a matchup of former champions.

The ninth seeded Roddick, the 2003 champion, will next face Mikhail Youzhny of Russia, who upset second seeded Rafael Nadal of Spain 6-3, 5-7, 7-6, 6-1 in their quarterfinal match earlier Wednesday.

On the women's side, world number one Amelie Mauresmo of France reached the semi-finals when she beat Dinara Safina 6-2, 6-3. Mauresmo will face third-seeded Maria Sharapova of Russia, who survived a tough battle with Tatiana Golovin of France, 7-6, 7-6.

And, second seed Justine Henin-Hardenne of Belgium beat 10th-seeded American Lindsay Davenport 6-4, 6-4. Her semi-final opponent will be Serbian Jelena Jankovic.

In fourth round men's play, world number one Roger Federer and American fifth seed James Blake both advanced and will face each other in the quarter-finals.

Federer of Switzerland ousted Frenchman Marc Gicquel, 6-3, 7-6, 6-3. Blake was a 6-4, 6-3, 6-1 winner over Tomas Berdych of the Czech Republic.

In other men's play, two fourth round matches that were halted by rain Tuesday were completed. Number-seven seed Nikolay Davydenko of Russia won six straight games to beat 17th-seeded Andy Murray of Britain, 6-1, 5-7, 6-3, 6-0.

Tommy Haas of Germany completed his match with a five-set win over 2000 champion Marat Safin of Russia, taking the decisive set in a tiebreaker, 4-6, 6-3, 2-6, 6-2, 7-6.