Venus, Serena Williams muscle into quarterfinals.(South Florida Sun-Sentinel)

WIMBLEDON, England _ It's cold, ruthless aggression that has taken Serena Williams to the top of women's tennis, and rarely has she been as relentlessly offensive against a top opponent as she was Monday in a rain-interrupted victory over Chanda Rubin.

It was mesmerizing to watch the consistent strength of her game. She drove Rubin off the court with slice serves to the deuce side, then battered the returns into the open court.

She struck thunderbolts, low and deep, even while backing up. Her serve was so dominating she faced only two break points, defending both, one with an overpowering 102-mph service winner. It was the only service game in which she was extended to deuce.

With two consecutive and decisive wins over her sister, Serena must be considered, at least until this Wimbledon is settled, the best player on the Sanex WTA Tour If she continues to play as she did in this latest 6-3, 6-3 bludgeoning, it's hard to see anyone beating her.

While Venus Williams has become tactically more like Jennifer Capriati, working the point six or seven strokes before going for the killer, Serena refuses to play anything but choke-hold tennis from the first ball off her racket.

She committed 19 unforced errors in this triumph that shot her into the quarterfinals. That's a lot for grass-court play, but she also had 35 outright winners, and who knows what the tab was on the errors she forced from the scurrying Rubin.

Serena is two wins from becoming No. 1 in the world for the first time in her six-year career. Even if she meets Venus in the final and loses, she becomes No. 1, and her sister slips to No. 2.