Yahoo Japan Corp., which runs Japan's leading Web portal, is switching to the Google search engine effective by yearend allowing the rival of its U.S. co-owner to dominate the world's third-largest online search market.

The deal between Yahoo Japan and Google announced Tuesday also allows the latter access to the former's auction and shopping sites data.

At present, Yahoo Japan has a 57 percent share of Japan's Web search market while Google holds 38 percent of it.

Yahoo Japan uses co-owner Yahoo Inc.'s search engine technology. However, Yahoo Inc. could no longer support the technology for Yahoo Japan after the U.S. co-owner forged a deal with Microsoft Corp. last year to use the latter's Bing search engine.

Yahoo Inc. has one-third stake in Yahoo Japan. Japanese cell phone and Internet service provider Softbank Corp. own a 40 percent controlling stake.

Yahoo Japan Chief Executive Masahiro Inoue said switching to Google was for the best interest of the company but will not change the company's relationship with Yahoo Inc.