Serena Knocks Out The World #1

(CNN)Serena Williams reached the quarterfinals of the Australian Open after surviving a severe test against world No. 1 Simona Halep. The American dropped her first set of the tournament and was pushed all the way by the Romanian in a thrilling match which ended 6-1, 4-6, 6-4. It had all started so easily for the American. Williams wrapped up the opening set in just 20 minutes, dropping just one game to the struggling top-seed, but the Romanian fought back to take the second.