Sundar Pichai, CEO of Google Inc (NASDAQ:GOOGL) and its subsidiary Google, testified under oath on Monday in a significant antitrust battle with the U.S. government. The trial aims to determine if Google engaged in illegal practices to maintain its dominance in search and parts of search advertising. If the government succeeds, Google might have to abandon certain business practices that have contributed to its continued dominance.

During his testimony, Pichai made several points. He criticized Microsoft (NASDAQ:MSFT)’s Internet Explorer, stating that before Google’s Chrome browser was launched, the browser market had stagnated, and Microsoft was not motivated to improve their product. Pichai described Chrome’s introduction in 2008 as a “pretty dramatic improvement” over existing options. He also emphasized that Google allowed users to easily change the Chrome browser’s default search engine, even if it wasn’t Google.

As a witness for Google, Pichai is expected to address the company’s investments aimed at maintaining its dominance in online search, especially in the era of smartphones. The government’s cross-examination is likely to inquire about the substantial sums Google pays annually to smartphone manufacturers like Apple (NASDAQ:AAPL) and carriers such as AT&T (NYSE:T) to ensure Google remains the default search engine on their devices, a practice that has contributed significantly to Google’s prominence in the advertising market, its primary source of revenue.

Google contends that its revenue-sharing agreements are legal and that the company has made substantial investments to keep its search and advertising businesses competitive. Google also argues that dissatisfied users can easily switch to alternative search providers if they wish.