Serena Williams looked to be cruising to a victory in Tuesday's (ET) Australian Open quarterfinals match against Karolina Pliskova with a 5-1 lead in the decisive third set, but she appeared to suffer an ankle injury and dropped six games in a row to lose the match.

"My ankle seems to be fine," she told reporters. "I don't usually know until the next day. I think she just played lights out on match points, hitting lines."

She added, "I like to kind of just tough it out," when explaining why she didn't call over the trainer despite appearing to limp at times in between points as she lost her lead.

The ending of the match was shocking given how Williams dominated the second and majority of the third set and was on cruise control for stretches. While Pliskova won the first set with an early break, Williams notched two late breaks in the second set and steamrolled her way to two quick breaks in the third to put herself in position to win.

However, a costly foot fault and the injury—along with Pliskova's impressive ability to stave off multiple break points and take advantage of Williams' miscues—ended her run at a 24th career Grand Slam and eighth Australian Open title.

It also marked the first time since 2014 that Williams lost in the Australian Open prior to the semifinals, and she won the tournament in 2017 while she was pregnant.

Pliskova's 6-4, 4-6, 7-5 win put her past the quarterfinals Down Under for the first time in her career as she chases her first Grand Slam.

She will face No. 4 seed Naomi Osaka in the semifinals after the latter defeated No. 6 Elina Svitolina in straight sets in Tuesday's other quarterfinals match. Pliskova is 2-1 against Osaka in her career.