A judge has ordered Google to open up Android to rival third-party app stores.
The ruling is part of Epic Games' blockbuster antitrust case against Google.
Google said it plans to appeal the ruling and ask the courts to pause implementing remedies.
A US judge has ruled that Google must open up Andriod for third-party app stores.
The ruling, made on Monday, was one of several remedies in the landmark antitrust case brought against Google by Epic Games, the company behind the video game Fortnite.
The remedies aim to give Android users more options for downloading apps and paying for transactions within them.
The judge ruled that for three years, Google will not be able to pay companies to launch apps exclusively on the Play Store or pay them to preinstall the company's app store on devices.
The judge also ruled that Google must allow competition app stores to access Google Play apps and that it cannot require app makers to use Google Play Billing.
The remedies are set to take force from November.
Shares of Google's parent company, Alphabet, fell 2.4% following the ruling.
In a statement posted online, Google said it was appealing the decision.
"The Epic verdict missed the obvious: Apple and Android clearly compete. We will appeal and ask the courts to pause implementing the remedies to maintain a consistent and safe experience for users and developers as the legal process moves forward," the company said.
"We will keep advocating for what is best for developers, device manufacturers, and the billions of Android users around the world."
The remedies follow a jury's finding last year that Google had violated antitrust policies in its Play Store for Android systems. The jury found that the tech giant held a monopoly in its Play Store for Android operating systems that limited the reach of competitors' apps and drove up prices for processing in-app purchases.
A spokesperson for Epic Games referred Business Insider to an X post made by the company's CEO, Tim Sweeney.
"The Epic Games Store and other app stores are coming to the Google Play Store in 2025 in the USA — without Google's scare screens and Google's 30% app tax — thanks to victory in Epic v Google," Sweeney said in the post.
The Epic Games ruling is Google's latest setback as it faces other antitrust cases affecting different parts of its sprawling business.
In August, a federal judge ruled that Google violated antitrust laws to keep a monopoly on search. Google projected it could lose $30 billion if it lost its default spot on Apple devices. A judge is expected to outline potential remedies for that case this week.
Separately, the Department of Justice is suing Google for its dominance in digital advertising. The ongoing trial could result in the internet giant's breakup.
Last month, Europe's top court upheld a €2.4 billion ($2.67 billion) antitrust fine against Google after ruling in 2017 that it used its search-engine dominance to favor its own comparison shopping service over competitors.