It will be one of the biggest antitrust cases in Europe since regulators went after Microsoft.

Europe's competition chief, Margrethe Vestager, is expected to make an announcement in Brussels later today and say that Google has abused its dominant position.

Google has a 90 percent share in the region's search market. If Europe is successful in making its case, the American tech giant could face a huge fine and be forced to alter its business practices to give smaller competitors like Yelp greater prominence in its search queries.

Margrethe Vestager, Europe's antitrust regulator, will visit Washington this week to participate in two antitrust conferences.

She is likely to find herself at odds with the US government which has made it clear that does not have a problem with its companies ruling the world.

In an internal memo to employees, Google expected the commission to file a statement of objections about how the company displays search results, particularly for shopping. It also expected the authorities to open an investigation into Android, the Google software that runs a majority of the world's smartphones.

Google thinks it is fine

Google thinks it has a strong case, with especially good arguments when it comes to better services for users and increased competition.

"Consumers have a lot of choice — and they are exercising it. And many, many other companies have very successful mobile businesses — including Apple, the most valuable (mobile) company in the world."

It is starting to get messy for US companies in the Old Country. Europe's antitrust officials have already opened investigations into whether Apple and Amazon received preferential treatment in their low-tax arrangements.

European lawmakers have said that these inquiries are not specifically aimed at American tech companies, though many industry executives say they are aimed at helping European tech companies, which have so far been unable to rival their much larger United States competitors.

Europeans want blood

More than two dozen companies and organizations have filed antitrust complaints in Europe against Google. Many are in Germany, where powerful publishing groups and online firms have called on the European regulator to stop the American search giant from blocking competition in sectors like online mapping, travel services and shopping.