Williams and Azarenka progress
Serena Williams, pictured, plays Li Na in the semi-finals in Cincinnati (AP)
Top seed Serena Williams comprehensively ended Simona Halep's impressive campaign to set up an intriguing semi-final with defending champion Li Na at the WTA Western & Southern Open in Cincinnati.
The Romanian's run to the last eight included the victory over Marion Bartoli which sent the Frenchwoman into retirement, but she had no answers against Williams, slipping to a 6-0 6-4 defeat.
Li was handed a walkover into the semis when fourth seed Agnieszka Radwanska withdrew from the tournament to attend her grandfather's funeral.
The other semi-final will be between second seed Victoria Azarenka and Jelena Jankovic.
Azarenka battled past Caroline Wozniacki, the Danish 10th seed, 6-3 7-6 (7/5), while Jankovic was a 6-0 6-4 winner over Italy's Roberta Vinci.