Venus Williams Falls to Radwanska in Sony Ericsson Open KEY BISCAYNE, Fla. - Venus Williams stared straight ahead, her left hand resting on her leg, waiting for the half-dozen fresh balls needed for the 17th game of the match to be rolled out. The balls remained relatively unused, it turned out. Once they arrived, Williams was broken at love to end a 6-4, 6-1 loss to fourth-ranked Agnieszka Radwanska on Wednesday in the quarterfinals of the Sony Ericsson Open. After a competitive first set in which Williams struck 20 winners and 19 unforced errors, her lack of energy in the second set cost her dearly, and her ratio of winners to unforced errors fell to 9 to 19. Only 7 of the 23 first serves Williams hit in the second set exceeded 100 miles an hour. She was out-aced by the slow-serving Radwanska, 4-3, in the match. The drop-off in Williams's speed from her previous matches was apparent from the beginning Wednesday, as she lost the first seven points. But she tightened the proceedings considerably as the set continued, keeping points short with opportunistic approaches to the net, especially off her returns of Radwanska's serve. The tactic worked effectively at first, to combat fatigue brought on by the autoimmune disease Sjogren's Syndrome, which Williams announced she had when she withdrew from the United States Open in September. "If I'm not feeling my best, then it becomes mental and I have to fight," Williams said of the challenges brought on by her ailment. You have to fight and fight and fight. Today I just I didn't conquer it mentally. I have to be there mentally more than the next player. Williams, who had won three-set matches in the second, third, and fourth rounds, said that midtournament changes in her recovery routine might have hurt her performance. "I woke up in a coma today," Williams said with a laugh. "After a while you start to feel like maybe everything's behind you," she said. I definitely learned, maybe if you're doing something right, don't change it. The disappointment of her loss aside, Williams seemed to recognize that the tournament was a success for her. "I could have had this result on Day One," she said with a smile. This is definitely a start. With her run to the quarterfinals, she will rise about 50 spots in the world rankings into the top 90, but is still well short of the Olympic qualification cut-off, which she has stated as a goal. She is scheduled to compete again next week at the Family Circle Cup in Charleston, S.C. Venus's younger sister Serena also fell in the quarterfinal stage to a counter-puncher, losing to an inspired Caroline Wozniacki, 6-4, 6-4, on Tuesday night. Though she is nearly a decade younger than Venus Williams and ranked 130 spots higher, Radwanska said she felt she had "nothing to lose" against her. Of course she's not No. 134 in the world," Radwanska said of Williams. She's for sure a top-five player. She's grand champion. Doesn't matter the ranking, actually, this week.