WASHINGTON Microsoft chief executive Satya Nadella is expected to testify on Monday as a witness for the U.S. Justice Department, according to a filing on the docket of its once-in-a generation court fight against Alphabet's Google.

THE TAKE

The government is likely to ask Nadella about Microsoft's efforts to expand the reach of Edge and Bing, its browser and search engine, and the obstacles posed by Google's dominance. Google will likely argue that the better quality of its products are the reason for its success rather than illegal behavior.

CONTEXT

* The government has argued that Google, which has some 90% of the search market, illegally paid $10 billion annually to smartphone makers like Apple and wireless carriers like AT&T and others to be the default in search on their devices in order to stay on top.

* The clout in search makes Google a heavy hitter in the lucrative advertising market, boosting its profits.

(Reporting by Diane Bartz; Editing by Howard Goller)