If she breaks Serena at all, she'll be pleased.
Serena does have her "horrible off days" as Mackem says. Last week she was pushed to a tie break by Putintseva (WR 108) and bagelled by Medina - Garrigues (WR 58).
I'm hoping she'll find Laura very frustrating (and we won't!) Thrilled that they are getting to play each other anyway.