WASHINGTON, Sept 12 (Reuters) - The United States will argue on Tuesday that Google did not play by the rules in its efforts to dominate online search, as a trial seen as a battle for the soul of the internet gets underway before a federal judge in Washington.

The U.S. Justice Department is expected to detail how Google paid billions of dollars annually to device makers like Apple Inc, wireless companies like AT&T and browser makers like Mozilla to keep Google's search engine atop the leader board.

Google's defense is simple: It will argue that its overwhelmingly high market share is not because it broke the law, but because it is a fast, effective search engine. It is also free.

Consumers, Google's lawyers will argue, can delete the Google app from their devices or simply type Microsoft's Bing, Yahoo or DuckDuckGo into a browser to use an alternative search engine. They will argue that consumers stick with Google because they rely on it to answer questions and are not disappointed.

The trial, which begins with opening arguments on Tuesday and is expected to run up to 10 weeks, has two phases. In the first, Judge Amit Mehta will decide if Google has broken antitrust law in how it manages search and search advertising.

If Google is found to have broken the law, Judge Mehta will then decide how best to resolve it. He may decide simply to order Google to stop practices he has found to be illegal or he may order Google to sell assets.

The government, in its complaint, asked for "structural relief as needed" but did not define it.

The legal fight has huge implications for Big Tech, which has been accused of buying or strangling small competitors but has insulated itself against many accusations of breaking antitrust law because the services the companies provide to users are free, as in the case of Google, or inexpensive, as in the case of Amazon.com.

Previous major antitrust trials include Microsoft, filed in 1998, and AT&T, filed in 1974. The AT&T breakup in 1982 is credited with paving the way for the modern cell phone industry, while the fight with Microsoft is credited with opening space for Google and others on the internet. (Reporting by Diane Bartz; Editing by Jamie Freed)