New York, September 3:

Serena Williams posted her easiest victory yet at this US Open, showing no ill effects from a lingering thumb injury to beat French No 10 Marion Bartoli 6-3, 6-4 on Sunday and reach the quarter-finals.

A few hours later, 12th seeded Venus Williams defeated Serbian teen No 5 Ana Ivanovic 6-4, 6-2. Through four rounds, the Williams sisters — both two-time US Open champs — have won every set. That kept them on track for a family reunion in the semi-finals.

Venus will play No 3 Jelena Jankovic, who beat No 19 Sybille Bammer 6-4, 4-6, 6-1 while Serena will face No 1 Justine Henin in the quarter-finals at a third consecutive major, having lost to her at the French Open and Wimbledon. Henin beat No 15 Dinara Safina 6-0, 6-2.

The day’s biggest surprise came when 88th-ranked Ernests Gulbis of Latvia ousted No 8-seeded Tommy Robredo 6-1, 6-3, 6-2. Men’s matches on Sunday were in the third round, and No 2 Rafael Nadal advanced beating Jo-Wilfried Tsonga 7-6 (3), 6-2, 6-1. Next up for Nadal is a fellow Spaniard, No 15 David Ferrer, who was one point from defeat before coming back to eliminate 2002 Wimbledon finalist David Nalbandian 6-3, 3-6, 4-6, 7-6 (5), 7-5 in a match that included a 24-point game.

Winners included No 3 Novak Djokovic, No 17 Carlos Moya, No 20 Juan Ignacio Chela, No 23 Juan Monaco and unseeded Stanislas Wawrinka, who followed up his win over Marat Safin by defeating Robby Ginepri 5-7, 6-4, 4-6, 6-4, 6-3. Moya also won in five sets, edging Philipp Kohlschreiber 4-6, 7-5, 7-6 (5), 4-6, 6-4, while Djokovic edged Juan Martin del Potro 6-1, 6-3, 6-4.