Luxembourg - Top-seeded Roberta Vinci of Italy reached the Luxembourg Open quarter-finals by beating Anne Keothavong of Britain 6-4, 6-1.
Venus Williams, playing her first tournament since the US Open, also advanced with a tough 7-6 (7/4), 6-4 victory over German Mona Barthel. Williams prevailed despite six double faults and losing her serve four times.
Also, Andrea Petkovic of Germany, ranked 182nd, defeated third-seeded and former No 1 Jelena Jankovic of Serbia 7-5, 6-0, while Daniela Hantuchova of Slovakia defeated Kirsten Flipkens 6-4, 4-6, 6-2.
Flipkens had won 24 of her previous 26 matches to give her a career-high No 58 ranking.
In another second-round match, Ksenia Pervak of Kazakhstan beat sixth-seeded Sorana Cirstea of Romania 7-6 (7/4), 6-1.
Results from the fourth day of the Luxembourg Open on Thursday (x denotes seeding):
Roberta Vinci (ITA x1) bt Anne Keothavong (GBR) 6-4, 6-1
Venus Williams (USA) bt Mona Barthel (GER x9) 7-6 (7/4), 6-4
Andrea Petkovic (GER) bt Jelena Jankovic (SRB x3) 7-5, 6-0
Ksenia Pervak (KAZ) bt Sorana Cirstea (ROM x6) 7-6 (7/4), 6-1
Daniela Hantuchova (SVK) bt Kirsten Flipkens (BEL) 6-4, 4-6, 6-2
Monica Niculescu (ROM) bt Julia Goerges (GER x2) 6-4, 6-2