Carlsbad: A. Radwanska d. Hantuchova

Late-afternoon sun launched the shadows of three light posts across the court in Carlsbad. By then, Agnieszka Radwanska's counter-strike skills had already obscured the openings Daniela Hantuchova worked so hard to create.

Radwanska relied on her accuracy and shrewd court sense to deconstruct Hantuchova, winning five of the final six games in a 6-3, 6-3 victory that sent her into her ninth quarterfinal of the season.

The second-seeded Radwanska spent some time in the stands watching younger sister Urszula upset sixth-seeded Jelena Jankovic, 6-2, 4-6, 6-3, immediately before her match. When the world No. 4 took the court, she set about shrinking the open spaces for Hantuchova to target.

The 45th-ranked Slovak partnered former No. 1 Martina Hingis in her successful doubles return last night, and today Radwanska showed that Hingis-like ability to disorientate by shifting her speeds, altering angles, and refusing to miss on key points in beating Hantuchova for the third time in the last four years at this event.

Radwanska, who looked a little weary in losing to Dominika Cibulkova in the Stanford final on Sunday, consistently beat Hantuchova to the ball. She broke three times in the opening set and defended her sometime-suspect serve effectively, winning eight of nine first-serve points.

When she's timing the ball well, former world No. 5 Hantuchova generates good depth from her clean, sweeping strokes. In the early stages of the second set, Hantuchova began attacking any sub-70 M.P.H. second serve she saw, often lashing returns down the line. A flat forehand return down the line set up a crunching forehand winner cross-court as Hantuchova broke for 2-1 with a firm "Come on!" Radwanska responded immediately, coaxing three consecutive errors to break back at love for 2-all.

The quandary Hantuchova faces in this match-up is she can't gain traction in running rallies with the quicker Radwanska, and she doesn't own that jolting power to end points with a single swing—so she's compelled to play closer to the lines or try to drive the ball down the line. Hantuchova fought off a break point with a forehand volley winner—she won 11 of 13 net points and would have been wiser to try to press forward even more—for 3-all, but that was her last stand.

Watching Hantuchova try to hit through Radwanska was like trying to watch a boxer beat up a shadow: The harder she swung the more the force dissolved. Radwanska held at love for 4-3, then broke for 5-3 when Hantuchova sprayed an inside-out forehand wide of the sideline.

The 2011 champion played a much cleaner match—she committed just 13 unforced errors while Hantuchova hit 41 errors—in the 80-minute victory, raising her Carlsbad career record to 10-1. Radwanska will face fifth-seeded Samantha Stosur for a semifinal spot.