That is not Serene Williams, but Mrs Treasure.
are you able to verify that, AvS? nearly every other hit of the same image i've discovered online suggests that it's Serena Williams, though it's equally possible that they're all emulating the same mistake.
Yes, that's an old Treasure (Victoria Dominguez) pic - one that most of the internet outside of our small community of muscle fans got wrong. This picture's quality is awful, but if you look closely you can see a tattoo on the middle of her back that matches Victoria's spider tat. Serena has no tats there.