Rakuten, one of Yahoo’s close competitors in Japan, has filed a petition to the Fair Trade Commission against the search engine tie-up between Yahoo Japan and Google. This goes in opposition to Yahoo Japan’s previous plan of using Microsoft search engine.

“We want the FTC to fully review the deal,” said company spokesman Naoki Mizushima.

With 10,000 petitions per year, the watchdog declined to comment.

The plan was for Yahoo Japan to take on Google search engine to cover their wide array of customers, a move that has already been criticized by Microsoft as well. This structure targets to dominate the domestic search market, and Rakuten believes will fetter progress in the country’s internet industry.

However, Microsoft doesn’t think this is such a big deal, particularly as it’s already raised concerns over the partnership between Yahoo Japan and Google.  The partnership came as a surprise to Microsoft earlier this year, as it gives Google a dominant position in the Japanese market, and complicates its own relationship with Yahoo back in the U.S.

It would be necessary for the FTC to conduct a review should there be any complaint, though no formal petition has been filed yet. Moreover, analysts say that they do not expect a petition to completely plug up the deal. Yahoo Japan told FTC that they will stay in line with anti-trust regulations.

Rakuten is seeking e-commerce expansion as well, with its own partnership with China’s major search tool, Baidu.  The two have invested a great deal in a new online mall, launched earlier this week.