A software company, Qihoo 360, that morphed overnight to challenge China’s dominant search engine Baidu, has adaptability in its blood. The flexible business strategy that built Qihoo 360 Technology Co. and its 360sou search engine is at the center of commercial row with Baidu, legal threats, stock sell-offs and a backlash from critics who question the company’s technology.

Qihoo, best known as an anti-virus software maker, launched the engine in mid-August and adjusted its existing browser – one of the most popular among China’s Internet users – by scrapping a navigation bar link to the Google search engine. In Google’s place, Qihoo installed a browser box directing quick searches to 360sou. The tweak yielded immediate results: Within a week, 360sou had grabbed more than 10 percent of all online searches in China.

From nowhere, the site suddenly became the second-largest search engine in China after market leader Baidu, bumping Google from the No. 2 slot and soaring past minor Chinese search engines Sogou and Tencent.

Before the change, Qihoo’s browser was the original source for 70 percent of all Google China searches and 20 percent of Baidu’s.