Serena Williams wants to serve an ace on yo face ... with a new cosmetics line.

The tennis great filed legal docs to trademark "Aneres" (spells Serena backwards, btw). Serena had already locked down the name a while back, but it was for her clothing line. It looks like she now plans to slap her backwards name on a variety of beauty products. Boss move.

Serena's cosmetics vision includes skin care prep and makeup removing products, colognes and perfumes. There are also makeup kits, bath soaps, lipstick, lip gloss, eye shadow, eyeliner and mascara.

Kylie, your competition has arrived.