Vanessa joined fellow co-star Rosario Dawson at the Egyptian Theatre in LA and looked as different from the cropped-haired, pregnant teenager character she plays in the movie as she possibly could!
Vanessa, 25, is having a very sexy and glamorous week after turning many heads in a plunging gold gown at a Golden Globes after party on Sunday night.
And Tuesday's sexy black Giorgio Armani dress had a similar flavour with yet another low-cut neckline and figure-skimming silhouette.
We also love the way she kept her look young and slightly less formal by going for a really simple, tousled hairstyle.
This style is very much a half-up, half-down do and is ridiculously easy to do at home. Here's how...
1. First, apply mousse to clean, damp hair, then roughly dry it all over using the diffuser attachment to help add volume.
2. Next, use a curling wand to create soft waves from around ear-level down to the ends of your hair. We're big fans of BaByliss Curling Wand Pro, £24.99, boots.com.
3. Backcomb the underneath layers of your crown area, then roughly part your hair just off-centre. Loosely scoop the front of your hair back, using your thumbs to part your hair horizontally from above your ears.
4. Try lifting one side of your scooped hair over the other at the back of your head to add a bit of thickness at the centre, then push the whole lot up slightly and fix with plenty of Kirby grips.
5. The key to this look is to make it look as tousled and laid-back as you can, so if bits fall out at the front leave them, and if your pinning isn't perfect, even better!
It really is that simple.
What do you think of Vanessa's cute half up-do? Let us know your thoughts below. Our fave comment across the site each week wins £50!
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