Meta Platforms Inc. and TikTok-owner Bytedance Ltd. have formally challenged the European Union’s latest clampdown on the dominance of Big Tech firms, paving the way for a fresh legal fight between regulators and the social media powerhouses.

Meta argued that the European Commission was wrong to put Facebook’s Marketplace and Messenger services within the scope of the bloc’s new digital antitrust rules, according to an appeal filed to the EU courts on Wednesday. The legal challenge sets up a battle in the courts with EU lawyers against the bloc’s Digital Markets Act, which is designed to rein in market abuse.

Lawyers for Bytedance argued its hugely popular social media platform shouldn’t be hit by the rules. In a blog post on Thursday, the company said TikTok is “the most capable challenger” to rival social media giants.

“This appeal seeks clarification on specific points of law regarding the designations” under the DMA, a Meta spokesperson said on Wednesday. “It does not alter or detract from our firm commitment to complying with the DMA.”

The commission declined to comment.

The DMA forces Meta to obtain users’ permission before sharing their data between Marketplace and other Meta-owned services. It will also require Messenger to work with rival online messaging platforms, once the obligations become enforceable next March.

More broadly, the act will make it illegal for certain platforms to favor their own services over those of rivals. They’ll be barred from combining personal data across their different services, prohibited from using data they collect from third-party merchants to compete against them, and will have to allow users to download apps from rival platforms.

Alphabet Inc.’s Google Search, Apple Inc.’s Safari and Amazon.com Inc.’s marketplace are among the 22 platforms covered by the DMA. Apple is also set to file an appeal against the inclusion of some of its services.

Meta is already embroiled in a dispute with the EU after the European Commission in December complained that the California-based company crushed competition from classified ad rivals by tying the Facebook Marketplace to its massive social network. Meta, which is fighting the accusations in the EU, has settled a similar case launched by the UK’s competition watchdog.

--With assistance from Stephanie Bodoni.