Yelp Study Says Google Is Cheating in Search

New research claims that Google is gaming its search results in its own favor to the detriment of competitors.

Google has “increasingly developed and promoted its own content as an alternative to results from other websites,” according to the report co-authored by Michael Luca, a Harvard Business School economist, Tim Wu and the Yelp Data Science team.

And yes, Yelp, which lists reviews of businesses, is a competitor that has cried foul over Google search results in the past. Perhaps more to the point, Tim Wu is a former advisor to the Federal Trade Commission, which settled a suit with Google in 2013. In January 2013, Wu defended the FTC’s decision to settle, writing that Google won search results because it was a better search engine, not because of its wealth and influence in Silicon Valley and Washington D.C. power corridors, according to Re/Code.

Wu, has changed his mind about that, citing changes in how Google search works.

He told Re/Code:

Those are very strong words. In 2001, a federal judge ruled that Microsoft acted in anti-competitive ways by parlaying its monopoly power in Windows into other areas of computing, namely web browsers. This judgement was thrown out on appeal, in part because the judge talked to the media while still hearing the case.

This research comes at a touchy time for Google which faces an antitrust investigation by the European Union.

Fortune reached out to Google for comment and will update this story as needed.

This article originally appeared on Fortune.com