Is the ASROCK N68C-S UCC crossfire compatible?

I've had this Mobo around 5 months now running fine with my XFX ATI 5770 Gcard, however i want to buy another 5770 and Crossfire them but when ive looked at my Mobo it doesnt look like it has another slot to support the crossfiring, i know it has Expansion Slots:1 x PCI Express x16, 1 x PCI Express x1 and 2 x PCI slots but i still aren't entirely sure if it will work? any help would be great. I suppose it doesnt help that the bloody cards huge, i can only see one of my 2 'spare' slots with it in.

Thanks ! Stuart