Weak demand for Apple's second-rank new handset, the iPhone 8, is tipped to weigh on the tech giant's profits this week.
The flagship iPhone X features an overhauled design and costs up to $2099 but does not go on sale until Friday in limited supply.
The cheaper iPhone 8 hit shops on schedule in September and its first few days on sale will be included in Apple's quarterly report on Friday.
Analysts and mobile industry sources report slow sales for the smartphone. Its design is the same as its predecessor, with a handful of technical upgrades, and some Apple fans are thought to be awaiting the arrival of the top-of-the-range iPhone X.
Market research suggests demand for the iPhone has been lower than for previous new models. Only 16 per cent of US iPhone buyers in the last quarter opted for the iPhone 8, according to Consumer Intelligence Research Partners, compared to 43 per cent who bought the iPhone 7 in the same period a year ago.