RadRR

Placing a white towel in front of her seat like a welcome mat, Agnieszka Radwanska spent time on changeovers tapping her toes on the cloth. Even when she wasn't busy playing points, Radwanska looked like a woman going places. She then reeled off six straight games to close a comprehensive 6-4, 6-1 victory over a lethargic Venus Williams and roll into the Sony Ericsson Open semifinals for the first time.

It was Radwanska's first win over Williams in nearly six years and just her second victory over the former No. 1 in seven meetings. The fourth-ranked Radwanska raised her 2012 record to 24-4, with all four losses coming to top-ranked Victoria Azarenka, her potential semifinal foe.

Playing her first tournament of the year as she wages an ongoing battle with the energy-sapping Sjogren's Syndrome, the 134th-ranked Williams is well aware that she's bound to confront physical peaks and valleys in her comeback, but she hit the wall today. Venus moved beautifully in her three-set win over Ana Ivanovic on Monday night, but was a step slow today and spent stretches of the second set looking like a woman running uphill.

If you prefer slam-bam tennis, you may not appreciate Radwanska's subtle skill set, but when she's on, she's one of the more entertaining players to watch. The Pole possesses shrewd court sense, exquisite touch, and is a highly-accurate player adept at taking the ball early and creating space for her shots. The fitter, fresher player, she won seven straight points to open the match. The pair combined for four straight breaks midway through the opening set before Radwanska took charge, holding at love for 5-3.

Signs of fatigue from Williams were clear. If you've watched Venus throughout her career, then you know she's one of the quickest women off the mark running down drop shots, but Radwanska beat her with angled droppers so decisively that the American wasn't even near the ball at times. The five-time Wimbledon winner had some success attacking net in an effort to shorten points, and saved two set points to hold for 4-5. That was effectively her last stand. Radwanska, who hit six aces combined in her last two matches, smacked successive aces to seal a 46-minute first set.

Both posted positive numbers in the first-set winners to errors ratio—Radwanksa hit 11 winners against five errors while Williams had 20 winners and 16 errors—but Radwanska was a shot better and played much cleaner tennis than the listless Venus in the second set.

The wild card nearly belted a forehand into the back wall in a horrific, four-error fifth game as Radwanska broke at love for a 4-1 second-set lead. Williams covered her face with her towel then slumped back in her chair during the ensuing changeover. Radwanska's second serve is the weak link in her game—Williams won 10 of 15 points on her opponent's second delivery—but she compensated by connecting on 74 percent of first serves. She'll need to sustain that pace against either Azarenka or seventh-seeded Marion Bartoli, both aggressive returners.