Samsung has blamed "unexpected" high demand for supply problems that are delaying the roll out of its latest smartphone.
Mobile networks Sprint and T-Mobile said the Galaxy S4 would go on sale later than expected because of a delay in shipments.
In a statement, Samsung said: "Due to overwhelming global demand of Galaxy S4, the initial supply may be limited.
"We expect to fulfil inventory to meet demands in the coming weeks."
T-Mobile said online orders for the phone will start on April 29 - not this Wednesday as planned - because of "an unexpected delay with inventory deliveries".
Sprint said it would take orders on the internet from Saturday, but the phone would be sold at stores only when it becomes available.
Samsung's head of sales and marketing said the global roll-out of the S4, which is being sold in South Korea on Friday, would go ahead as expected the following day.
"Demand is far stronger than we had expected and as a result we are having difficulties in fully meeting initial supply requests," Mr Don-joo said.
The new Galaxy is thinner and lighter than the popular S3 model, and has a high-definition five-inch screen.
The South Korean company overtook Apple to become the world's top smartphone maker, and in January said it had shipped more than 40 million Galaxy S3 units since its launch in May.
Supply issues have affected other global launches of popular smartphones - with some customers waiting weeks to receive new iPhones in the past.
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