Maria Sharapova overpowered world number one Victoria Azarenka to set up a meeting with Serena Williams in the final of the WTA Championships.
The Russian prevailed 6-4 6-2 after 96 minutes of baseline battling in Istanbul.
Game six in the second set lasted 15 minutes, before Sharapova finally broke for a 5-1 lead.
"I have lost to Victoria a few times so I was happy to get the chance to play against her," said Sharapova.
"Against the world number one, you have to run down every ball. She's number one for a reason so I had to be ready for every shot.
"It will be a difficult match against Serena. She's been on fire and she's the one to beat."
Williams had earlier secured her place in the final with a straight-sets win over Agnieszka Radwanska.
