Apple claims demand for its new iPhone 6s and 6s Plus could surpass the record-breaking sales of iPhone 6 last year, as the newest versions of the of the firm's smartphones go on-sale.
The new iPhone 6s, which was unveiled earlier this month, has much the same design, but comes with an improved camera in both the front and rear of the phone, as well as a pressure sensitive screen - where users can press more firmly in order to open new shortcuts - a feature Apple calls 3D Touch.
The technology giant said that pre-orders were "on pace" to match those of the iPhone 6 launch in September last year, when that device went on to sell more than 10 million units in the first three days, and help Apple post world-record profits.
The new phone also comes with a rose gold finish on the rear casing for the first time.
Phil Schiller, Apple's head of worldwide marketing said: "Customer response to the iPhone 6s and iPhone 6s Plus has been incredibly positive, we can't wait to get our most advanced iPhones ever into customers' hands starting this Friday.
"iOS 9 is also off to an amazing start, on pace to be downloaded by more users than any other software release in Apple's history."
Queues had already started to form outside the Apple retail store in Regent Street, London, on Thursday as technology fans looked to be one of the first to get their hands on the new phone, which starts at £539.
The launch, which was starting at 8am, marks the beginning of busy autumn for the technology giant, who also announced a new, larger iPad earlier this month, which is set to be released in November.