The win puts the Lady Chargers (10-8 overall) in the Class 5A North Half finals against against the winner of New Hope and Ridgeland.
"From the first whistle Oxford was better than us today, there's no doubt," Starkville coach Anna Albritton said. "They wanted it more...They were excellent today."
Starkville (11-5-1) won the regular-season meeting 1-0 on a last-minute goal.
Saturday's win marked the Lady Chargers' third consecutive victory.
"I think it's all about peaking and we're just peaking at the right time," Sanford said.
Like the Lady Chargers, the Starkville Jackets (12-3) also achieved a level of vengeance by knocking off the Oxford boys 4-2.
"We said today we were going to come out with a lot of fight and they did that," SHS coach Brian Bennett said. "Today we just went after it."
Kase Kingery, Justin Gordon, Juan Salazar and Taylor Wise each scored goals for Starkville, while Hunter Stewart and James Lear netted goals for Oxford (13-3-3).
Starkville advances to host Hernando in the Class 5A North Half finals on Tuesday.