Serena Williams KO From The AO After Shock Loss

After being just moments away from victory, Serena Williams has suffered a shocking collapse to be bundled out of the Australian Open in the quarter-finals.

Williams, the tournament's 16th seed, had been up 5-1 in the deciding third set against Karolina Pliskova and looked on course to cruise to victory.

But in an uncharacteristic capitulation, the American lost six straight games to go down 7-5 in the third.

The final scorecard read 6-4, 4-6, 7-5 to Pliskova, the seventh seed. She will now go through to the Open's semis, to meet Naomi Osaka for a place in the final.

(AAP Image/Ritchi Tongo)

Williams battled an ankle issue through the match, and appeared to fade badly as the third set wore on.

It was an epic comeback from the Czech challenger, who had been been facing match point with Williams up 40:30 and 5-1 in the third set at one point.

Many were quick to note the sudden collapse from Williams and surge from Pliskova.

More to come.