Deutsche Telekom AG suffered a blow at the European Union’s top court in a potentially precedent-setting dispute over its right to compensation for having to tie up money earmarked for a multimillion-euro antitrust fine that was slashed after an appeal.

The European Commission is challenging a lower EU court’s decision last year to award Deutsche Telekom €1.8 million ($2 million) for the harm caused by the watchdog’s “refusal to pay it default interest” on the amount of a cartel fine which the company had already paid.

The lower court’s ruling should be dismissed and with it Deutsche Telekom’s victory, Advocate General Anthony Collins of the EU’s Court of Justice said in a non-binding opinion on Thursday. The Luxembourg-based court follows such advice in a majority of cases.

The challenge is seen as a test case for several other pending disputes, including one by Intel Corp. The chipmaker is seeking €593 million in interest from the commission following a historic court victory that overturned a 1.06 billion-euro antitrust fine last year.

In Thursday’s case, Deutsche Telekom was fined €31.1 million in 2014 for stifling internet rivals, but on appeal the fine was cut by about €12 million, which was repaid to the firm. The firm then sought compensation on default interest it said the commission should have paid it back as well.

A positive outcome for Deutsche Telekom in the court’s final ruling could force EU regulators to pay back millions of euros in interest to companies they’ve charged for breaching antitrust rules.

The case is: T-236/22 Intel Corporation v. Commission.