Samsung is expected to unveil its latest Galaxy smartphone at a launch shrouded in secrecy.
The electronics giant is said to be anticipating sales of its new handsets to be as high as 10 million per month.
But it has kept tight-lipped about the design of the mystery product which has been at the centre of much hype in the run-up to its launch.
A teaser picture was published online on Tuesday showing only a shadowed image of the top of a dark handset.
Samsung Mobile US posted the shot on Twitter, writing: "The countdown for #TheNextBigThing has begun. Who's ready for the Global Unpacked Event on March 14?"
Pictures of what was claimed to be the new S4 were released earlier by a Chinese forum.
But observers have questioned the legitimacy of the photographs which show a device with a larger screen than the previous model.
While Samsung has refused to give anything away in terms of what customers can expect from their mystery offering, experts believe the highly anticipated S4 handset could seriously disrupt the mobile phone market.
Among its predicted features are a five inch screen, wireless charging capability and a 13-megapixel camera which would be able to take 360 degree pictures.