Google isn't worried about Bing or Yahoo. The company has set its eyes on Amazon and is bent on getting back the millions of searches lost to Amazon as more and more people go directly to Amazon to search for things they wish to buy.

Google has rebranded its competitor to Amazon Prime and is charging customers a yearly subscription of $95 for Google Express, formerly Google Shopping Express, effectively undercutting Amazon's $99 yearly subscription fee for Amazon Prime. For the price, buyers get unlimited free shipping with same-day delivery on all orders $15 and up.

Google Express is only available in select cities in the U.S. and has just expanded to Boston, Chicago and Washington D.C. Amazon, on the other hand, offers free shipping but buyers will have to wait for two days to get their orders, although the e-commerce company free shipping covers all states except Alaska, Hawaii and Puerto Rico.

Also, Amazon has a much broader selection than Google, although Google Express could edge out Amazon in the local marketplace with its partnerships with local retailers such as Paragon Sports in New York City, Treasure Island Foods in Chicago and Stop & Shop in Boston. Amazon, too, has Amazon Fresh, a $299 a year program that delivers fresh produce and perishable produce to buyers in select areas. Google is also experimenting with its own fresh foods delivery program but is currently limited to the Bay Area.

Google Express service has shifted out of beta to include a number of other retailers, such as Barnes & Noble, Vitamin Shoppe, 1-800-Flowers, PetSmart and Sports Authority. Asked why some retailers, notably retail kings Target and Whole Foods, did not sign up with Google Express' expansion, Google vice president of Google shopping and overseas product search advertising Sameer Samat says the company is not expecting many retailers to expand their reach at this time of the year.

"We've worked hard to make sure everyone can get their store operations in order to manage this expansion," Samat says. "Some are choosing to come right away and some may come later. That's up to them. We're entering Q4. It's a challenging time for everybody to manage expansion of any kind of new program."

Google has also shortened its free trial from six to three months. Buyers who opt not to become a Google Express member can still purchase goods from the service and pay an additional $4.99 for shipping, a price less than half of what Amazon charges for non-Prime members.