Many also note that Apple launched its new line of smartphones a week later this year, so its fourth quarter results will include just two days of sales, versus the eight included in its fourth quarter 2014 results.
Analysts expect Apple to report earnings per share of $1.88 on revenue of $51.1 billion, according to Thomson Reuters. That is just above company guidance for the 2015 fourth quarter of $49 billion to $51.1 billion and would represent a 21 percent jump over last year.
When it comes to predicting just how much demand for the latest version of the company's new smartphones may have slowed, expectations vary widely.
"Given how much consumers use smartphones, we believe the incremental value of the newest iPhone model will continue to justify its purchase for the vast majority of iPhone buyers. However, we will be watching closely to see if consumers begin to opt for savings over new features," Pacific Crest Securities analyst Andy Hargreaves wrote in a report earlier this month.
But Alex Gauna, analyst at JMP Securities, said Monday that bearish analysts are missing Apple's potential in global markets.
"I think there are a lot of investors that are worried about the tough compares from the 6 to the 6S, as well as the saturation, arguably, in North American and Western markets," Gauna said on CNBC's "Squawk on the Street." "But what that fails to takeinto consideration is the still-massive global opportunity for Apple."
Hargreaves expects Apple's fourth-quarter results to be in line with consensus expectations, but guidance for Q1 revenue will fall short of the Street estimate of $76.4 billion.
"We continue to believe Street estimates for the first half of fiscal 2016 iPhone units are too high, but Apple's price and the stickiness of iPhone customers should protect long-term cash flow, which creates favorable long-term risk/reward," Hargreaves wrote.
Tigress Financial Partners' Ivan Feinseth said he's less worried about the number of iPhones sold, and more interested in the amount of profit from them — a number he expects to be strong, he told CNBC's "Power Lunch."
"Even if the reaction in the stock is negative, I believe the report will be positive, and Apple as a stock is so unbelievably cheap, I think it will over time, continue to go higher," Feinseth said.