Apple debuted the iPhone 6 and iPhone 6 Plus in mid-October on the Chinese mainland.

"The market is very unpredictable, and many things can happen that will change how vendors perform in this quarter," Wang said. "If Apple fails to continue to excite the market, it will lose out, especially with the market being so highly competitive."

This month has seen a number of strong players release flagship products.

Xiaomi, an affordable phone maker, released its first phablet similar to the iPhone 6 Plus in size and appearance, but at a fraction of the price.

Motorola Mobility LLP, now a Lenovo Group Ltd smartphone subsidiary, also introduced three models to compete with Apple at the middle and high segments of the market.

Apple is looking to open 40 brick-and-mortar stores in China by mid-2016.

The company opened its 14th store on the mainland on Saturday in Hangzhou, Zhejiang province.

"Apple's entry into smaller cities in China will increase its brand presence and shipment volumes," said Wang from Canalys.

"However, it is not likely that the majority of consumers who have relatively limited income will spend a lot to buy an iPhone," she said.