“It was definitely a match I had to be really focused for, because she's a really good player. She's one of those late bloomers where she tends to get better and better as every year goes on in her career. I was probably playing the fittest girl on tour,” Serena told the tournament’s official website.

“Serena was playing too well for me today,” Dementieva concluded.

Dementieva still has a chance of reaching the last four if she beats fellow Russian Svetlana Kuznetsova on Friday.

But if she fails, Venus Williams will progress from the group along with her younger sister.

Venus got her first win of the tournament on Thursday against Kuznetsova in three sets, 6-2, 6-7, 6-4.

Meanwhile, it’s still all to play for in the White group.

Caroline Wozniacki overcame a bout of cramp to defeat come up with the third Russian upset of the night. She took the better of Vera Zvonareva in three sets, 6-0, 6-7, 6-4.

The Dane will definitely reach the semis if she beats Jelena Jankovic later today, who also needs a victory to be sure of progressing.