MELBOURNE, Australia - Six-time Australian Open Serena Williams scored her 17th career win against a reigning World No.1 inside Rod Laver Arena on Monday night, as she came through a highly-anticipated round of 16 match with top seed Simona Halep to reach her 13th career quarterfinal at the Australian Open, 6-1, 4-6, 6-4. 

After being pushed the distance by Halep after leading by a set and a break, Williams ultimately came through a tense end to the match in which she saved three break points in a key sixth game of the final set.

The former World No.1 earned the lone break of serve in the seventh game of the final set, as she saved a game point before breaking Halep for the fifth time in the match overall in back-to-back games which helped decide the match.

As it happened: Serena soars past Halep in classic clash inside Rod Laver Arena

Halep managed to extend the match for one hour and 47 minutes, as she bounced back after being blitzed in a first set that lasted just over 20 minutes, where she broke to love to start the match before losing the next six games. 

After surrendering serve for the fourth time in five service games, the Romanian trailed 6-4, 2-1 before sealing her first break of the match, and hung with the 23-time major champion through the duration of the middle set before sealing it with back-to-back games of her own. 

Asked afterwards about her approach as Halep fought back into the match, Williams said: "Well, I mean, that's why she's No.1. She literally lifted her game to a new level. I didn't.  I kind of stayed at the same level and I should have looked at my game as well.

"But it's a part of this journey on my way back. You know, it's 10 months, so I can't be too upset at myself. I felt like I did have an opportunity to win that in straight sets, but then I'm playing the No.1 player in the world.

"So I'm still learning, which is, at my age and my point in my career, I think admirable and exciting that I still have things I can learn from.

"I feel like each day, each match, and each tournament I'm learning something, and I think today I'm just learning that I have to fight for titles. I have to fight for matches."

Up next, Williams will face No.7 seed Karolina Pliskova in the last eight for the second straight major, as she defeated the Czech in the quarterfinal round en route to a runner-up appearance at the US Open. 

Williams added: "We have had good matches. She's beaten me on an occasion or two or three. She's always someone that comes out and serves big and plays well.

"I've got to return a little bit better the next time that we play but I will be ready. She's ready, I'm ready, and let's do it."