To much juice there,I think the over at -120 at The Greek is the better value,cause if she hangs were looking at 6-3,6-4,just enough to get over the 18.5 total..
I firmly believe that Petkovic can stay with Dementieva. Elena gave up 10 break points and was broken 3 times against Pavlyuchenkova. Pavlyuchenkova actually gave up less break points (6) but Dementieva was able to take advantage on 5 occasions to win 6-4 6-4.
Petkovic is pretty solid on her serve so I think she can definately cover the +6 spread. However, the juice is too much to play here so I've done the same thing that you have, backed the total to finish over 18.5 games at -112.
Petkovic looked absolutely terrible yesterday in her win over Rezai. Petkovic didn't win the match, Rezai lost it. She won in 3 sets and looked terrible. Rezai had 2-3 straight break points in almost all of Petkovic's service games in the 3rd set and just couldn't get that final point. There were at least 3 straight service games for Petkovic where she was down either 15-40 or 0-40 and still won the game because Rezai was that terrible. If Petkovic plays like that today Elena will smoke the shit out of her. That's one problem to think about tho, today is a different day and could be a different Petkovic. I still love Dementieva.