Karolina Pliskova has pulled off the comeback of a lifetime on Wednesday, surviving four match-points against 23-time Grand Slam champion Serena Williams to claim a 6-4, 4-6, 7-5 victory and secure her place in the Australian Open semi-finals.

While the Czech world number seven got off to a flying start and won the first set, Williams began to find her groove in the second and broke Pliskova's serve twice in the third.

"I was pushing her. I was more aggressive... but suddenly I lost momentum and I was not playing the same game which was working," Pliskova said after the match.

"I stopped a little bit. Obviously she took her chance. She just went for it. She went for her serves. She went for the returns. She was just putting pressure on me. I was more passive."

"I didn't have many chances in the third set, I was a bit mentally down."

With the score at 5-1 in the final set and with Pliskova staring down the barrel at 4 match-points, it appeared almost certain Williams would advance in the tournament.

"Suddenly I got a chance too. That's how it is in tennis. You need luck sometimes because this is I think not happening often, maybe once in lifetime," Pliskova said.

"I went for it. I just said, maybe this match is over, but let's just try to win this game."

"I was with the wind, which kind of helped me little bit. I just went for my shots. She got a little bit shaky in the end so I took my chances and I won."

The famous victory now means 26-year-old will take on young Japanese sensation Naomi Osaka for a place in the final of the Australian Open.