` She 's older than me Serena Williams pushes past Caroline Wozniacki in WTA Finals semi . Simon Halep beats Marta Sánchez in other semi . Romanian humbled the world No . 1 in group stage earlier in the week . Williams looking to clinch a fifth WTA Finals title ; Halep reaches final in first appearance .
Serena Williams pushes past Caroline Wozniacki in WTA Finals semi . Simon Halep beats Marta Sánchez in other semi . Romanian humbled the world No . 1 in group stage earlier in the week . Williams looking to clinch a fifth WTA Finals title ; Halep reaches final in first appearance .