NEW YORK: The remarkable comeback of Kim Clijsters gathered pace at the US Open on Wednesday, underlining her growing threat to the domination of the Williams sisters.

The 26-year-old Belgian defeated 14th seed Marion Bartoli of France 5-7, 6-1, 6-2 to reach the third round.

In just her third tournament back after a two year "retirement" during which she got married and had a baby daughter, 26-year-old Clijsters started slowly but moved up through the gears to stun the former world top tenner.

She will next play another Belgian, Kirsten Flipkens, for a place in the last 16, where she could run into Venus Williams, who is struggling with a knee injury.

The 29-year-old American, who won back-to-back titles here in 2000 and 2001, wore a heavy white strapping to support her left knee in her tie against compatriot Bethanie Mattek-Sands, but she was rarely stretched and won 6-4, 6-4.

Younger sibling Serena, who is in the same half of the draw, later produced an awesome display of power hitting to demolish Hungary's Melina Czink 6-1, 6-1 and reinforce her position as the tournament's outstanding favourite.

Williams apart, other leading seeds to make it through from the second round were eighth-ranked Victoria Azarenka of Belarus, who coasted past Barbora Zahlavova Strykova of the Czech Republic 6-2, 6-1, and seventh-seeded Russian Vera Zvonareva, who hit back to defeat compatriot Anna Chakvetadze 3-6, 6-1, 6-1.

In-form Italian Flavia Panetta, the 10th seed, recorded the first whitewash of the tournament, defeating India's Sania Mirza 6-0, 6-0, but China's top player Li Na kept Asian hopes alive with a 6-1, 6-3 win over tempestuous teen Michelle Larcher de Brito of Portugal.

In other games, French veteran Amelie Mauresmo lost 6-4, 6-0 to Aleksandra Wozniak and said she would consider her future in the game at the end of the year, while Maria Kirilenko of Russia upset Polish 12th seed Agnieszka Radwanska 6-4, 2-6, 6-4.

Bartoli was in command early on against Clijsters as both players struggled to hold their serves and she took the first set when Clijsters overcooked a forehand drive and then played a poor drop shot from 30-all on the French player's serve at 6-5 up.

But the Belgian, who won her only Grand Slam title here in 2005, varied her shot-making at the start of the second and Bartoli quickly unravelled as she was knocked out of her comfort zone.

The deciding set was all Clijsters with Bartoli looking increasingly tired and frustrated.

Venus Williams, who came within three points of a shock first-round loss to Vera Dushevina of Russia, said she was trying to play through the pain of her injured knee.

Williams will next play Slovakian suprise Magdalena Rybarikova with a likely fourth round matchup with Clijsters looming at the weekend should they both win.

Sister Serena, the defending champion and second seed who is seeking a fourth US Open title and a 12th Grand Slam title overall, took just 53 minutes to dismantle the unfortnate Czink in what was the first time a women's match had concluded the night-time session on the Arthur Ashe Stadium court. LINK