It wasn't the heat this time. It was Serena.
Serena found herself a set and 0-3 down to an inspired and flawless Vika. Vika played great but Serena was definitely not herself. A lot of that was Vika's quality hitting and surprising court coverage, which put more pressure on Serena. On top of that, Serena was definitely not having the serving day she had against Sam and was unable to get a lot of free points on her serve and she was clearly feeling less than 100% physically.
So Serena did what A-Rod did yesterday. She started hitting out and shortening points, taking cracks at Vika's weak serve, and it worked. She quickly asserted herself and climbed back from the 0-3 hole to force tight tiebreak that saw her come out on top 7-4. From there, you knew it was pretty much over. Vika, to her credit (and you know how reluctant I am to ever give her anything but shit) did her best to stay with Serena in the third. But after she was broken rather quickly you could see that she knew there was nothing she could do. Credit to her for taking it like a champ and walking off with her head held high, racquets intact. Nothing to be ashamed of here.
So the "dream final" of Serena vs. Justine is still a possibility. But they'll have to get through China first.