Amazon is extending its everyday delivery system to include Sundays allowing prime members to place an order as late as Friday and get the delivery on Sunday through unlimited two-day shipping.

Amazon Inc., the biggest chain of online retail store, is expanding its everyday delivery system so customers can get shipments throughout the week. The e-commerce giant announced Thursday that customers in 15 new cities across the U.S. will receive their orders even on Sundays, so Amazon Prime members can take advantage of the unlimited two day shipping to place orders as late as Friday and receive their products on Sundays for free.

According to the company, expanding Sunday delivery system from Los Angeles and New York metro areas to new postal areas has resulted in millions of deliveries on Sunday. The new cities under Amazon's Sunday delivery, includes Austin, College Station, Houston, Dallas, San Antonio and Waco in Texas; Cincinnati and Columbus in Ohio; Lexington and Louisville in Kentucky; New Orleans and Shreveport in Louisiana; Indianapolis, Indiana and Philadelphia, Pennsylvania.

"So far, the most common items delivered on Sunday include baby supplies such as newborn apparel, books and toys-Sunday delivery is clearly crossing errands off the weekend to-do list," Mike Roth, Amazon's vice president of North America operations, said in a press release, Thursday. "We know our Amazon customers love the convenience of everyday delivery, and we're excited to be offering Sunday delivery in more cities across the U.S."

The latest expansion follows Amazon's vigorous attempts to fight new rivals challenging its dominance in retail space. Earlier this week, Google started off its same-day delivery service called the Shopping Express in Manhattan and some parts of Los Angeles. Amazon, however, offers its same-day delivery in 12 cities including Dallas, Los Angeles and San Francisco, which were recently added.

Through expanding the Sunday delivery, Amazon is strengthening its position in the retail space. The retailer recently renovated its online store by dedicating a section exclusively for wearables, so customers can easily find what they are looking for and compare different products in the range.