Last time Venus played JJ...she lost 60 61...and JJ leads the head to head...both JJ and Venus have not been playing that well...so I don't think you can be so sure JJ won't win...
Yeah, on clay, when Venus was playing her first tournament back from injuring herself in Miami. That also coincided that Jankovic was playing her best tennis of the year, and having taken out Indian Wells earlier and making her run to the final in the same tournament that she inflicted that loss upon Venus.
This is grass, Venus's surface. Jankovic may have beaten her in 2006, but she's a good step and a half slower now then she was then, her weapons have disintergrated some what and she is no longer fearless. Factor in that her confidence is near an all time low, and things don't look that great for her.
and Given Jankovic's Grandslam record outside of Roland Garros over the past two years, there's a high possibility that she gets upset before the third round
And Venus has hardly been playing at all, so how can you assume she's playing badly? She beat the world number 11 and 17 in her first two matches back, and dominated Ivanovic. Sure, she went out to Hantuchova, but she got the match play she wanted.