Apple pulls back the curtain on Tuesday on its latest innovations, amid frenzied anticipation over new big-screen iPhones and possibly an "iWatch" which could shake up the world of wearable computing.
A mystery event set in San Francisco has pumped up expectations for Apple to unveil a stunning new device to its line-up of iPhones, iPads, iPods, and Macintosh computers.
"Apple's iWatch category launch will be one of its most important and brand-reinforcing launches in years," Forrester analyst James McQuivey commented Monday in a report indicating a quarter of adult US Internet users anticipate buying wearable computing devices in the coming year.
"Apple will show again how computing platforms are won or lost on the one-two punch of eager consumers and hungry ecosystem partners."
- Old-time Apple magic -
Apple is seeking to show that it hasn't lost its world-dazzling magic when it comes to innovation, and  to shift attention from a recent celebrity photo theft scandal.
Apple has been customarily tight-lipped ahead of the event at a performing arts center where late Apple co-founder Steve Jobs introduced the Macintosh computer 30 years ago.
But those who follow Apple are expecting bigger versions of the iPhone and -- perhaps more significantly -- an entry into wearables with an "iWatch."
The choice of venue has fueled talk that Apple will crash the wearable computing party with a smartwatch, in a bid to dominate the segment the same way it ruled smartphones, tablets and MP3 players with iPhones, iPads and iPods.
Apple chief executive Tim Cook has stated that wearable computing makes more sense on the wrist than in eyewear such as Google Glass.
Work on a wrist-worn computing device with a heath theme is believed to have begun years ago at Apple, inspired by famed co-founder Steve Jobs and his battle with an illness that took his life in 2011.
Apple is fine-tuning a new mobile operating system that could allow for mobile payments and includes a health platform, which could mesh nicely with an "iWatch" for tracking activity, sleep, pulse and more and connecting to an iPhone or iPad.
Confidence is high, and timing is right, for Apple to introduce new-generation iPhone 6 models with screen sizes stretched to tap into love for "phablets" combining features of smartphones and tablets.
"Frankly that's one of the things they need to do to improve their standing in the market," Forrester analyst Frank Gillett said of iPhones getting bigger.
"Much of the market popularity of smartphones has been driven by large screens."
An Adobe Digital Index report found that people prefer screens larger than five inches when browsing the Internet on mobile devices.
Browsing the Internet on smartphones with four-inch screens, like those on iPhones, dropped 11 percent during the past year, according to the report.
Apple has seen sales growth for iPhones, but slower than its rivals like Samsung, which sells an array of big-screen smartphones.
The iPhone has a leading share in the US market of some 40 percent, but its worldwide share of the smartphone market is less than 12 percent, according to surveys.
- Gigantic pent-up demand -
Gartner analyst Van Baker predicts Apple will unveil an iPhone 6 with a screen increased to 4.7 inches, and that odds are strong for a 5.5-inch version.
"There is gigantic pent-up demand for a larger iPhone," Creative Strategies president Tim Bajarin told AFP.
"Apple will likely have a monster fourth quarter."
New iPhones are expected to feature near-field communication chips that will let them be used as mobile wallets, challenging services such as Square or Google Wallet.
Apple would be asking people to trust it with health and more financial data after taking a bruising over the release of nude photos of celebrities including Oscar winner Jennifer Lawrence from its cloud.
Apple says there was no breach of its iCloud and that the celebrities had their accounts hacked by using easy-to-guess passwords, or by giving up their personal data to cybercriminals posing as Apple.
Cook told the Wall Street Journal that Apple would step up its iCloud security by sending alerts when attempts are made to change passwords or access iCloud data on new devices.