Serena Williams of the US advanced to the quarterfinals of the Australian Open on Monday after a hard-fought 6-1, 4-6, 6-4 victory over Romanian world No 1 Simona Halep.The 37-year-old shone at the Rod Laver Arena to again demonstrate her remarkable longevity and ability to compete at the game's highest level, reports Efe news."It was an intense match and there were some incredible points," Williams said on court after the match. "I really needed to elevate my game. She's the number one player in the world."The number 16 seed started strongly, storming into a comfortable lead before taking the first set 6-1 as the number one seed Halep struggled to get a foothold in the match.After bossing the opening exchanges, Williams let her opponent back into the contest as Halep took the second set 6-4.The American broke Halep's serve in the seventh game of the third set to go 4-3 up; she was soon serving for the match at 5-4, sealing the win on the first of two match points.Williams advances to the last eight of the tournament as she continues her bid to add an eighth Australian Open title to her 23 career Grand Slam wins.