Serena Williams and sister Venus took their third doubles title at the Australian Open and eighth Grand Slam title as a combination Thursday, defeating Daniela Hantuchova of Slovakia and Japan’s Ai Sugiyama, who lost 6-3, 6-3 as they dodged a flurry of zingers at the net. “I just wouldn’t want to face them too much. They are ferocious,” Serena said of her taller sister’s fireballs. And she ought to know, because the dynamic duo have faced off against each other seven times in Grand Slam singles finals. “She’s covering the whole net. At one point today, I literally stood back and she took care of everything,” Serena said.