Serena Williams refuses to blame injury for collapse after shock Australian Open defeat to Karolina Pliskova

Serena Williams insists she has no excuses after a remarkable collapse against Karolina Pliskova sent her crashing out of the Australian Open.

The 37-year-old was 5-1 up in the final set and squandered four match points before going on to lose 4-6, 6-4, 5-7 to the no.7 seed.

The manner in which Williams threw away her seemingly unassailable lead was baffling to say the least, but pundits on Eurosport pointed out Williams had rolled her ankle which appeared to affect her game.

The timing coincided with the 23-time Grand Slam winner's wobble in the final set, but when quizzed about the incident, Williams was keen to play down the impact of the knock.

"My ankle is fine, maybe I'll feel it tomorrow," she told reporters.

"I didn't call the trainer out because I didn't feel I needed it.

"I think she played incredible on match points, just hitting lines."

It was a memorable day for Pliskova, who had only ever reached the semi-final at a Grand Slam once before - at the French Open in 2017.

And the 26-year-old was under no illusions about what she had achieved, describing the victory as her "best ever comeback."

"I was almost in the locker room but now I'm standing here as a winner so it's a very good feeling," she said in the post-match interview on court.

"My mind was in the locker room. It was tough because she was really playing well.

"I was a little bit passive, mentally down. I just said at 5-2 maybe I'm going to have a chance. She got a little bit shaky, I took my chances and I won."