First Teaser Poster For Nacho Vigalondo's Extraterrestrial

I'm looking forward to this one a great deal, and this enigmatic teaser poster has only stoked my little embers even more. Extraterrestrial – or, in its native Spanish, Extraterrestre – will be the second feature film from Nacho Vigalondo. As such, it has some promise to live up to, and very possibly, the reputation of a genre wizard to cement.

The film's official plot blurb:

Everyone knows what to do if one morning the sky would be absolutely full of UFOs: run as fast as you can. However, what would happen if the invasion started while you are in the flat of the girl of your dreams, the one you have just met?

So – what's the tennis ball about, would you guess?