Apple Inc.'s (AAPL) - Get Report shock sales warning last week, which it pegged to slowing demand in China, was echoed by its main rival Tuesday, but while Samsung Electronics (SSNLF) might have a smaller share of the world's biggest smartphone market, its business is inextricably linked to the world's second largest economy. 

Samsung said fourth quarter profits would likely come in at around 10.8 trillion Korean won ($9.67 billion), well shy of the market consensus of 13.2 trillion won, with sales falling 11% to 59 trillion won. Samsung only has a 1% share of the China handset market, compared to around 9% for Apple, but its chips and screens make their way into handsets made by Huawei Technologies, as well as Apple's iPhones, and that segment comprises a much larger portion of its operating profits.

"Operating profits sharply decreased due to lackluster demand in the memory division and intensifying competition in the smartphone sector," Samsung said in a rare explanatory statement alongside the earnings forecast. "Memory demand will rebound in the second half with the release of new CPUs and smartphones."

Both Samsung and Apple have grown increasing reliant on China sales to boost revenues and improve their bottom lines, with the Seoul, South-Korea-based tech giant generating, for the first time on record, more from China (27.4 billion Korean won) than from the United States (21.79 billion won) over the first half of last year.

Apple's China sales, meanwhile, grew 16% over the company's 2018 fiscal year, which ended in October, to $51.9 billion, and now represent about a fifth of total revenues. China sales are about a third of Samsung's total revenues.

Domestic handset makers such as Huawei, Xiaomi, Oppo and Vivo, however, have consistently grown their market share in China on the back of cheaper, more customer-focused phones that appeal to China's specific demands, such as photo enhancements and longer battery life.

That said, it's a market that's also slowing fast: According to the International Data Corp., China's mobile phone shipments fell 8.8% last year, nearly triple the 3.3% global decline, and will have no better than flat growth for the whole of 2018. China's Academy of Information and Communications Tech, a research institute directed by the Ministry of Industry and Information Technology, pegs the 2018 decline at 15.5%. 

Apple CEO Tim Cook said last week that this slowdown would likely mean group revenues for the three months ending in December would come in around $84 billion, notably shy of the Street consensus of around $91.5 billion and the company's own previous guidance of between $89 billion and $93 billion.

Cook pinned the weaker iPhone demand in China on several factors, including a slowing economy worsened by "rising trade tensions with the United States" and cited high prices tied to the strength of the U.S. dollar, fewer carrier subsidies and customers taking advantage of reduced battery replacements in the softened demand for new iPhones.

Apple shares were marked 0.4% higher at $148.52 in pre-market trading Tuesday, but hit a 20-month low of $142.19 last week to extend its three-month loss to around 38.6% and value the Cupertino, Calif.-based tech giant at just over $690 billion- down from $1.1 trillion on October 3.

Samsung shares, meanwhile, closed 1.7% lower today at 38,100 won each but have only fallen have as much as Apple over the past three months.

Samsung's saving grace, in that respect, may come from the fact that it's been able to turn its major smartphone rivals -- Apple and Huawei -- into key customers. Apple uses Samsung's OLED screens o some of its newer iPhones, and now makes up an estimated 25% of revenues for Samsung's display division.

That may not completely isolate it against an extend China slump, however, which market research group Canalys sees falling 3% to a five year low of less than 400 million units across the whole of 2019. 

"We believe the poor results owe mainly to the firm's semiconductors division, with its display earnings steady q-q (and slightly above our expectations), but this seems to have been negated by increased marketing expenses at the handset business," said Samsung Securities analyst MS Hwang. "The company's display division should benefit from the growing use of OLED panels and a rising number of applications, while its handset business has targeted reinforced market leadership."