Google's (NASDAQ:GOOG) Chrome is having an inauspicious start to 2012, slipping a tad to 18.9 percent market share through January from 19.1 percent through December, according to Net Applications.

Mozilla's Firefox browser, meanwhile, continued its slide, dropping nearly a full percentage point to 20.9 percent for the month, from 21.8 percent in December and 22 percent in November. Apple's (NASDAQ:AAPL) Safari browser's share also dropped-to 4.9 percent from nearly 5 percent the prior month.

Microsoft's (NASDAQ:MSFT) market-leading Internet Explorer was the biggest beneficiary of Chrome's and Firefox's falls. The incumbent hit 53 percent share, from 51.9 percent the prior month, regaining lost share from its rivals.

By any measure, Chrome had a fantastic growth spurt in 2011, when it started the year at about 10 percent market share, according to Net Applications. Chrome still stands to top 20 percent in the next few months, at which time it will likely tie or surpass the sliding Firefox.

Firefox's fall has been gradual and steady. The browser had about 25 percent market share when Chrome came to market in 2008 and has struggled to grow share ever since.

The Firefox team has ramped up its innovation pace to match the Chrome team's cycle of releasing a fresh browser build every six weeks. Firefox is on version 10; Chrome has propelled ahead to version 17.

Net Applications' calculations for mobile browser share tell a different tale.

Safari, which powers the iPad, iPhone and iPod Touch, commanded roughly 55 percent share through January, up from 53 percent through December. Opera Mini followed Safari at 19.6 percent, down from 21.7 percent.

Google's Android browser wielded 17.8 percent share, up from 15.9 percent for December. The Android browser, which lives on smartphones and tablets, is battling Opera Mini for the perennial No. 2 spot in mobile browser share, with Safari playing the role of IE.