I definitely think Barthel will be a lot more tricky than Venus. Venus isn't able to be consistent enough off the ground to match Vika anymore, whereas Barthel can occasionally string together good patches of play (like in Stuttgart and AO) which could be a lot more difficult if Vika is feeling sloppy.
Still it all depends on how well she's playing. Definitely needs to avoid a slow start. Good luck!
Just so you know: I'm better than you because my fave is better than your fave. Your fave is a bitch and a shrieking BBB. Or was it pusher? Who cares. She's a classless brat anyway. But don't you dare insult my fave, idiot.