WASHINGTON, May 3 (Reuters) - The U.S. government will

lay out its antitrust case against Alphabet's Google

on Friday in a second day of closing arguments focused on

accusations that the online search leader broke the law to stay

on top in search advertising.

U.S. District Judge Amit Mehta on Thursday peppered both

sides with questions seeking to better understand the case ahead

of making a ruling.

The Justice Department has hammered away at Google in a

trial that started on Sept. 12, arguing the search engine giant

is a monopolist and illegally abused its power to boost profits.

On Friday, Google and the government's lawyers are expected

to focus their arguments on claims that Google's business

contracts harmed competition for search advertising.

Witnesses from Verizon, Android maker Samsung

Electronics ( SSNLF ) and Google itself testified about the

company's annual payments - $26.3 billion in 2021 - to ensure

that its search is the default on smartphones and browsers, and

to keep its dominant market share.

Google has claimed that search advertising markets are

competitive, but the government asserts that the tech giant

manipulated ad auctions and could increase prices as wanted

without fear of harming business.

Mehta is expected on Friday to take up the government's

claim that Google intentionally destroyed internal documents

that were relevant to the issues in the lawsuit. The government

wants Mehta to presume that Google deleted chats that were

unfavorable to the company.

Google has defended its data preservation practices, calling

them reasonable, and urged the court not to sanction the

company.

Google is expected to tell the court that its "search

advertising technologies have proven to be incredibly valuable

to advertisers" and that "search and search advertising quality

and output have continually improved."

The court is not expected to issue an oral ruling at the

conclusion of the argument.

This case, filed by the Trump administration, was the first

of five aimed at reining in the market power of tech leaders.

The second, against Facebook parent Meta, was also filed

during the Trump administration, while Biden's antitrust

enforcers have followed with a second case against Google and

cases against Amazon.com ( AMZN ) and Apple Inc. ( AAPL )