ISTANBUL, Turkey - Ominously, for the rest of the draw at the TEB BNP Paribas WTA Championships - Istanbul, the best is yet to come from Serena Williams.
In her post-match press conference after defeating World No.1 Victoria Azarenka on Wednesday to complete a flawless Round Robin program, Williams claimed she is still not satisfied with her performance level in Turkey.
"Like I said yesterday, what I felt was really positive about my match is I know I can do better," Williams said. "I've been practicing really hard, and I actually expected to play a bit better and hopefully I can as the tournament goes on."
Williams' victory improved her head-to-head record this year against the Top 5 to 12-0, with five of these wins coming against the unfortunate Azarenka.
However, as in their memorable final at this year's US Open, Williams did not have things all her own way. Indeed, at the end of the contest, Azarenka was left ruing several missed opportunities, most notably the 3-0 second set lead she let slip.
"I had too many opportunities that I didn't use," Azarenka said. "I feel like I didn't keep my discipline. When I had the right play, I was in control most of the times, but I just couldn't do it consistently today."
Another cause for concern for the Belarusian will be the nine double faults she contributed to the Williams cause - many of which came at critical junctures, such as the two she hit when serving to stay in the first set.
Williams, on the other hand, often saved her best tennis for when it mattered most, turning the tide in the second set with a series of vicious returns and one scarcely believable running backhand pass.
This helped Williams to the first in a run of four unanswered games before completing her 64 64 win when an Azarenka second serve drifted long on match point.
Azarenka must now regroup ahead of her winner-takes-all encounter with Li Na on Friday to decide who progresses with Williams from the Red Group.
"I'll be sad for a little bit after today's match, but I'll bounce back strong for tomorrow," Azarenka added. "It's win or go home. I'll give everything I have to win because I want to stay a couple more days here and fight.
"I'm glad I have another opportunity to keep the dream alive."
Another player still dreaming of a semifinal spot is Sara Errani, who kept her hopes alive with a 63 26 60 win over Samantha Stosur.
"I think we played a good match.," Errani said. "She was playing amazing in the second, and I'm happy that I kept my focus and stayed aggressive on the third."
Errani's final match is against Agnieszka Radwanska, with the winner guaranteed a place in the semifinals.
"I'm happy to be here and I'm happy with how I'm playing. I just want to keep going.
"Radwanska is a very strong player. We've played some times before and I know her well. I hope it will be a tough match!"