It's in Apple's hands now.

Samsung Electronics Co Ltd.   (SSNLF)  confirmed its slowest quarterly profit growth in a year Tuesday as global smartphone demand slows and competition from low-cost rivals intensifies, putting even more pressure on its main rival, Apple Inc. (AAPL) - Get Report , to revive tech sector sentiment with its own earnings update later today.

Samsung said group operating profits came in at 14.9 trillion Korean won ($13.3 billion), a figure that modestly beat its own forecasts, published earlier this month, but still marked the slowest rate of profit growth since July 2017. Group revenues fell 4%, Samsung said, to 58.5 trillion won,  and higher marketing costs associated with the launch of its flagship S-9 smartphone weighed on profits in its mobile division, which fell 34% to 2.7 trillion won.

Samsung said it expects the smartphone business environment "to remain tough despite strong seasonality due to growing competition to offer higher specifications and lower prices" and that it hopes to "secure profitability by expanding sales of new models in each segment."

Samsung shares fell 0.54% in Seoul Tuesday, compared to a 0.05% gain for the benchmark KOSPI index, and closed at 46,200 won each, extending their year-to-date decline to around 9.5%.

Action Alerts Plus holding Apple is set to report its fiscal third quarter earnings after the close of trading Tuesday, with FactSet estimates suggesting the Cupertino, Calif.-based group will report Q3 EPS of $2.16 per share, a 29% increase from the same period last year, on sales of $52.3 billion.

Apple's third quarter numbers might be one of the more crucial reports for the sector in a number of years, given the sharp sell-off witnessed over the past five days following weaker-than-expected earnings from Facebook Inc. (FB) - Get Report and some disappointing subscriber numbers from Netflix Inc. (NFLX) - Get Report as the season kicked off.

Facebook, another AAP holding, beat Street earnings estimates by 2 cents a share with a $1.74 bottom line, but narrowly missed on revenue ($13.23 billion versus $13.36 billion) and spooked investors with warnings about rising costs and thinning profit margins, sending the stock into a historic tailspin that loped a single-day record $119 billion from its market value last week.

Amazon Inc. (AMZN) - Get Report , by contrast, smashed its second quarter estimate with earnings of $5.07 per share on sales of $52.89 billion. Alphabet Inc, (GOOGL) - Get Report , as well, impressed with earnings of $11.75 a share that beat the $9.59 forecast on sales of $32.66 billion that rose 25% from the same period last year.

Throughout this, the S&P 600 Information Technology Sector subindex has fallen more than 5.3% over the past five days, while the the NYSE's FANG+ index, an equal-weight collection of the world's biggest tech stocks, has fallen 8.33%. 

Samsung's mobile sector weakness, however, could suggest Apple will have a difficult time changing the market's perception for earnings growth over the second half of the year.

Last month, market searchers at CounterPoint said the iPhone 8 topped the Galaxy S9 as the world's top-selling smartphone, thanks in part to the latter's poor sales in Europe.

Samsung has a full-year handset shipments target of 350 million units - an upgrade from 320 million earlier this year and a figure it may need to revise if second quarter sales dip below the 72 million unit market . However, the impending August launch of its new Galaxy Note flagship could alter both the company's and investors' expectations.

Samsung is not only seeing increased competition from Apple and its new iPhone suite, but also from China-based handset makers, many of which are moving from their "low cost" reputation to the higher-end of the global market, especially as demand wanes.

Oppo, for example, China's second-largest handset maker, unveiled a €999 ($1,320) unit called the FindX while its domestic rival, Vivo, is marketing a $780 smartphone called the Nex.

That said, Strategy Analytics, a closely-watched industry benchmark, sees global handset sales only rising by 1.4% by the end of the year to 1.49 billion units, although 5-G network rollouts in 2019 and beyond should reignite appetite in the near-term.