Agnieszka Radwanska described Serena Williams' first set in their Australian Open semi-final as the best performance she has ever faced.
The Polish fourth seed was powerless in a 20-minute opening set on Rod Laver Arena on Thursday, before Williams closed out a 6-0 6-4 victory to reach her seventh final at Melbourne Park.
Williams was impeccable in the first set, smashing 18 winners and just four unforced errors while losing only seven points.
Asked if it was the best she had faced, Radwanska said she was powerless.
"I think so. There was just no mistake," she said.
"Unbelievable serve. Everything, she was going for it. I couldn't do much. Not at all, actually."
Radwanska only put in 54 per cent of first serves in her loss, and Williams took advantage - winning 16 of 24 points against her second serve.
The 2012 Wimbledon runner-up, who has now lost all nine meetings with Williams, said the 21-time grand slam champion was too good.
"I think the only thing that I could do better is if I put more first serves in, that would help for sure," Radwanska said.
"But otherwise I didn't really think that I was playing bad. I think she started unbelievably, with such a power and speed. I was just standing there kind of watching her playing.
"Well, I had my little chance in second set, especially when it was 4-4, but otherwise just too good."