Yandex may be the most popular search engine in Russia, but when Firefox 14 rolls out in the country Google will become the new default option for search. It's not clear why the decision was made, though Google and Mozilla did sign a three year revenue sharing agreement at the end of last year. Yandex currently enjoys an estimated 60 percent market share in Russia and became the default option for Firefox back in 2009. But while it's no longer number one, Yandex will be the second search option for Russian users, and as the company points out it will also be offering a customized version of Firefox with Yandex as the default. Yandex has also said that it doesn't believe the shift will impact its business too much, explaining that it "will have a minimal effect on its share of searches, and the impact on revenue and profitability will be negligible."