Companies up against Amazon.com Inc. (AMZN)  are ready to rumble.

Enter Walmart Stores Inc. (WMT) . On Monday, Aug. 21, the big-box retailer announced the expansion of its online grocery delivery service to the Dallas and Orlando markets, just ahead of a meeting set for Wednesday, when Amazon's $13.7 billion bid for upscale grocer Whole Foods Market Inc. (WFM) will be voted on by shareholders. If shareholders pass it, the transaction will be one step closer to completion.

Amazon's proposed acquisition, subject to regulatory approval, will give it access to Whole Foods' roughly 450 locations and allow the e-commerce conglomerate to build out distribution points for its own online grocery service, AmazonFresh.

Walmart's online grocery delivery expansion will be done through a partnership with Uber. The retailer will have its employees, acting as personal shoppers, prepare the online grocery orders and then an Uber driver will deliver them to customers' homes.

"We've been testing delivery in a number of ways for a while now," Walmart Ecommerce Vice President Mike Turner said in a statement. "In some areas, we're trying general merchandise deliveries led by associates. In others, we're testing grocery delivery using Walmart trucks and drivers."

A Walmart spokeswoman told TheStreet in an email on Monday that its online grocery service is in six markets. In San Jose, Calif., and Denver, Walmart has its own fleet of drivers to deliver groceries; in Phoenix, Tampa and now Orlando and Dallas, it uses Uber drivers. Walmart, operating 4,100 stores, also gives customers the option of ordering groceries online and picking them up at one of its 900 participating locations. 

The Amazon-Whole Foods deal, unveiled on June 16, has sent shock waves through the grocery space, as investors fear damage to Target Corp. (TGT) , Costco Wholesale Corp. (COST) and Kroger Co. (KR) . After all, Amazon's rise has led major traditional retailers, including Macy's Inc. (M) , J.C. Penney Co. Inc. (JCP) and Sears Holdings Corp. (SHLD) , to close hundreds of stores and lay off workers.

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