MELBOURNE, Australia — Serena Williams won her 19th Grand Slam title, continued her unbeaten run in six Australian Open finals and extended her decade-long domination of Maria Sharapova with a 6-3, 7-6 (5) victory despite a hacking cough on Saturday night. After celebrating prematurely on her third match point, letting her racket go before hearing a let call to what she thought was an ace, Williams had to quickly re-gather her composure. read more