MELBOURNE, Australia (AP) — The Williams sisters are back in the quarterfinals of a Grand Slam, and neither one is there just to watch.Venus Williams continued her impressive career resurgence at the Australian Open with a 6-3, 2-6, 6-1 win over sixth-seeded Agnieszka Radwanska on Monday night, reaching the last eight at a major for the first time since the 2010 U.S.