Walmart announced yesterday that it was partnering with Postmates to expand the retailer’s online grocery delivery ambitions. This new delivery option started in Charlotte, NC, as of yesterday, and will expand to more markets “in the coming months.”

The news comes less than a month after Walmart announced plans to expand its online grocery delivery service to more than 100 U.S. metro areas by the end of the year. Walmart has existing delivery partnerships with Uber and Deliv, which have been delivering groceries already in select markets. Same day grocery delivery from Walmart carries a $9.95 delivery fee and requires a $30 minimum purchase.

Not to be outdone, Amazon announced yesterday that its Prime customers in Los Angeles can now get free, two-hour delivery from Whole Food stores there. That the two announcements happened on the same day illustrates how fierce that battle is between Amazon and Walmart to bag your grocery business. The two have been locked in a tit-for-tat arms race (in-home delivery, anyone?) ratcheting up features and services to become your grocer of choice. Perhaps feeling left out, Target too announced yesterday its plans to expand its Shipt same day delivery service across Arizona and New Mexico later this month.

The added twist to the Walmart/Postmates announcement is that Postmates had reportedly discussed the idea of merging with restaurant delivery service DoorDash, according to Recode. Though nothing came of any such discussions, and Postmates denied the report, that move was supposedly motivated in part by Postmates and DoorDash wanting to fend off the ever-growing, all-consuming Amazon.

And if all that weren’t enough, last week Instacart confirmed that it had expanded its Series E with an additional $150 million to expand its same day grocery delivery ambitions. Instacart has partnerships with grocery retailers such as Albertsons, Kroger, Costco, and even Whole Foods.

All of this activity points to just how hot and important the same day grocery delivery space is for everyone involved. It’s hits the sweet spot where human laziness and hunger intersect. We’re always going to buy food, and if one of these players becomes our go-to grocer, they’ll reap a recurring weekly revenue source.