Microsoft Corp. scored an important win against rival Google Inc. over the weekend, as Amazon.com began using its technology to power the Internet retailer`s A9 search unit.

Microsoft`s new Windows Live is at the core of the company`s efforts to win online advertising dollars away from Google Inc. and Yahoo Inc.. A9 had previously been powered by Google.

Amazon`s search engine, A9, breaks down searches into various categories, such as Web searches, book searches, and blog searches. It is a stand-alone search site, www.a9.com, as well as the search technology used on the www.amazon.com Web site.

A9 Chief Executive David Tennenhouse told news agencies that Windows Live presented a "very interesting, powerful Web search option" that had previously been featured on the A9 site.

Tennenhouse said the Google search was removed from the site on Sunday, following the expiration of that contract. He would not comment on the terms of the Microsoft deal, or whether a new contract with Google had been an option.

Microsoft`s new search engine and user interface consolidates a variety of the software giant`s Web services such as search, e-mail, instant messaging and security at its Live.com site.

Senior product manager at Microsoft`s MSN Internet unit, Justin Osmer, confirmed that Google`s contract with Amazon.com had expired, but did not elaborate on what was behind the switch.