Apple is expected to say this week that it has sold more iPhones in China than on its home turf in the US for the first time last year, highlighting the shifting power balance of the smartphone market.
Analysts estimate that the US tech group reached the turning point in iPhone sales after expanding its presence in China last year via a deal with China Mobile, the country's largest network operator, and after the release of the latest iPhone 6 in the country in October.
The iPhone's growing market share in China comes as Samsung, the global market leader by smartphone volumes, has stumbled and the region has seen the rapid rise of low-cost challenger Xiaomi.
Tim Cook, chief executive, had said in 2013 that he expected China to eventually overtake the US as Apple's single largest source of revenue. The iPhone already accounts for more than half of Apple's total sales and an even larger share of its profits.