Second seed Andy Roddick and women's top seed Lindsay Davenport have reached the round of 16 at the Australian Open tennis tournament in Melbourne.

Roddick scored a straight-set win over Austrian Jurgen Melzer 6-2, 6-2, 7-5. In women's play, Davenport defeated Nicole Vaidisova of the Czech Republic in straight sets 6-2, 6-4.

Elsewhere in men's play, Australian third seed Lleyton Hewitt ousted Juan Igancio Chela of Argentina in four sets: 6-2, 4-6, 6-1, 6-4. Another Argentine player, sixth seeded Guillermo Coria, defeated former French Open winner Juan Carlos Ferrero of Spain in straight sets: 6-3, 6-2, 6-1.

In the women's draw, third seed and reigning French Open champion Anastasia Myskina of Russia advanced when her opponent Lisa Raymond of the United States withdrew with a stomach injury.

Eighth-seeded Venus Williams of the United States ousted Anna Smashnova of Israel 6-3, 6-0. Russian Elena Dementieva scored a three-set win over Slovakia's Daniela Hantuchova 7-5, 5-7, 6-4.