Serena's Stepmom to Judge: Tennis Star Is Locking Me Out of My Home!

Serena Williams allegedly hates her stepmother so much, she ordered the woman to vacate the family home immediately ... or else she'll change the locks.

At least that's the story Serena's stepmom told a judge in new docs filed in Florida ... in which she begs the court to stop Richard Williams from throwing her out on the street.

As TMZ previously reported, 75-year-old Richard filed for divorce from 38-year-old Lakeisha Juanita Williams back in June after 7 years of marriage. They have a son together.

Lakeisha claims Richard has ordered her out of the Florida home where they lived -- a home she claims is owned by his daughter, Serena Williams. 

In the court docs, Lakeisha says Serena's legal team fired off demand letters "requesting she and the child vacate the home and threatened to change the locks."

So far, Lakeisha refuses to budge.

Lakeisha has also filed an emergency motion begging the court to force the sale of another property they owned together because she needs the money.

She's also concerned Richard has "health issues" and could die -- and if that happens, his fortune could be tied up for years while the courts decide who gets what. She needs the cash, stat.