Amazon (AMZN) - Get Report may have just successfully shipped its first package by drone in the United States, but Walmart (WMT) - Get Report is also showing it won't be a slouch in the drone area by any means.

The e-commerce giant revealed on Friday that it successfully delivered a four pound package in California using an Amazon Prime Air delivery drone on Monday (video below). The delivery follows Amazon's private drone trial in the U.K. in December.

Walmart, similarly, was granted a patent on March 16 for a system where airborne drones locate an item "within a retailing shopping facility" and then carry that item to a delivery area within the same facility.

Walmart said in its application that drones would relieve pressure on overwhelmed store staff.

"There may not always be enough employees available to assist customers in as timely a manner as the customer might wish," the company said. "For example, an item that a customer wishes to purchase (or already has purchased) may be located in a non-public part of the retail shopping facility such as a back storeroom," requiring an employee to deliver that item by hand.

"With increasing competition from non-traditional shopping mechanisms, such as online shopping provided by e-commerce merchants and alternative store formats, it can be important for 'brick and mortar' retailers to focus on improving the overall customer experience and/or convenience," Walmart added.

Such improvements, both in stores and in e-commerce, are a renewed focus for Walmart as it competes with Amazon. The retailer has owned e-commerce startup, which it acquired for $3.3 billion, for about six months. founder Marc Lore, who now heads Walmart's e-commerce division, is snapping up niche online retailers like Moosejaw and ModCloth.

Even before Lore's arrival, Walmart began experimenting with autonomous and remote controlled drones in distribution centers to automate inventory checks.