Microsoft\'s Internet Explorer 8 is no longer the world\'s most-used browser, according to a Web analytics firm. But its replacement isn\'t a different version of IE: It\'s Chrome, Google\'s upstart Web browser. StatCounter, which tracks Internet data, said that IE8\'s share of the browser market fell to 23.5% in the last week of November, trailing behind Chrome\'s 23.6%. Since then, Chrome has expanded its lead. It now has nearly 25% of the market, compared to IE8\'s 22%. Chrome had been topping IE8 on weekends since the beginning of October, but Google\'s browser finally overtook Microsoft\'s for a five-day period a few weeks ago, StatCounter CEO Aodhan Cullen said in a blog post. \"It looks as if people favor Chrome on weekends at home, but office commercial use has now caught up,\" he said. Of course, IE8 is just one version of Internet Explorer. A growing number of people -- 10%, by StatCounter\'s measurements -- are using the more modern IE9. Many are also still using older versions like IE7 and, amazingly, IE6, which debuted in 2001. Combined, Internet Explorer still leads with a 38.5% share of the global browser market. Google\'s Chrome is second and Mozilla\'s Firefox is in third place, a percentage point behind Chrome. Chrome\'s lightning-fast rise significantly reshapes the playing field.The browser battle intensified this year, after a decade-long hiatus, as search competition between Google (GOOG, Fortune 500) and Microsoft (MSFT, Fortune 500) heated up. Searches made in Internet Explorer default to Microsoft\'s Bing, while Chrome and Firefox are both tied in with Google\'s search engine.In a constant attempt to one-up one another, the browser makers have been adding a slew of advanced features like extensions, synchronization, privacy, HTML5 support, and hardware acceleration. Google is so serious about staying up to date that it releases a new version of Chrome every six weeks. Finding itself in the unfamiliar position of trailing its browser competition, Microsoft plans to follow Google\'s lead and start implementing automatic updates to IE9 in January, the company recently announced.