MELBOURNE, Australia — It wasn't until Serena Williams forced herself to relax, and not focus too intently on a milestone Grand Slam title, that she rediscovered the art of winning the biggest events in tennis. Now she's on the verge of a 19th major championship after beating 19-year-old Madison Keys 7-6 (5), 6-2 on Thursday and setting up an Australian Open final against long-time rival Maria Sharapova. Williams has won all five Australian Open finals she has contested and won her last 15 matches against No.