The three-time grand slam champion lost 6-2 2-6 1-6 to the 95th-ranked Davis.

Kerber took the opening set in just 31 minutes and looked set to cruise to victory but the diminutive Davis, standing at just 5 feet 2 inches, stunned the German who took just three games from the last two sets.

It will be a very happy Fourth of July for the American, who only made it into the Wimbledon main draw as a lucky loser after suffering defeat in qualifying over the weekend.

The 25-year-old Davis will now play Spain's Carla Suárez Navarro Saturday.