Apple is expected to launch a larger, thinner iPhone 5 next Wednesday US time - just as Nokia and Motorola are preparing their own offerings to tempt Christmas shoppers.
The notoriously secretive company triggered speculation about the new handset yesterday when it invited journalists to an event in San Francisco - with an invitation that consists of the number 12 casting a shadow of the number 5.
Tech giants pencil in September fight
September marks the start of the US tech products parade with new gadgets from Nokia, Motorola, Amazon, Apple and HTC on the calendar.
The anticipated gadget would follow on from last year's iPhone 4S. But while that release introduced small cosmetic changes, this year's is expected to be radical - and the first big step by Apple since the death of company co-founder Steve Jobs in October last year.
Photographs of components reckoned to have come from Apple's many suppliers in China over the past five months point to a device with a larger 10.7cm (4.2in) screen and a thinner body, and a new nine-pin connector at its base replacing the 30-pin one on existing iPhones and iPads.
Current iPhones have an 8.9cm screen - measured diagonally - but even the expected larger size of the iPhone 5 will be smaller than the 12.2cm Samsung Galaxy S3. But Apple is expected to try other measures to compete with its South Korean rival.
Apple will also be aiming to increase its share of the crucial US Christmas smartphone market by seeking sales bans on the Galaxy S3 and Galaxy Note, plus eight other phones from Samsung's 100-plus range.
The iPhone 5 is also expected to offer 4G high-speed wireless broadband connectivity on US carriers, in common with a growing number of rival Android phones sold in the US.
In Britain Ofcom documents also suggest that Orange, which is setting up a 4G service in the UK the day before the launch, intends to offer iPhone compatibility. It is not clear if the Australian version will support local 4G networks.
Some analysts reckon the next iteration of the iPhone, first launched in 2007, could sell up to 160m units worldwide in its first two quarters. That compares with about 80m for the iPhone 4S, according to estimates by Horace Dediu, founder of the Asymco consultancy.