Apple confirmed that the pre-order sales of its iPhone 6 and iPhone 6 Plus surpassed 4 million units during the first 24 hours of the pre-sale last week. The response by Apple fans exhausted the inventory, delaying the shipments of pre-ordered devices as late as October.

Apple's latest achievement outbids the pre-sale record set by iPhone 5 in 2012. Apple sold 2 million iPhone 5 units through pre-orders during the first 24 hours of availability and pushed 5 million units during the first weekend sale. Apple's iPhone 6 and iPhone 6 Plus will go on retail sale this Friday at 8 a.m. local time, with analysts estimating the sales to go up to 10 million, according to Computer World. This means the iPhone 6 sales will surpass last year's iPhone 5S and iPhone 5C record sale of 9 million units in the first weekend. The four-million iPhone 6 pre-orders equals to the total number of iPhone 4S sold during the first three days in 2011.

With such an impressive demand for new flagships, Apple might be outstripped of supplies. The iPhone 6 Plus has a greater demand than its smaller 4.7-inch version. Customers ordering the iPhone 6 Plus witnessed delayed shipping almost immediately last Friday. Currently, Apple's online store is showing 7 to 10 days for shipping the iPhone 6 and 3-4 weeks for the iPhone 6 Plus.

"Demand for the new iPhones exceeds the initial pre-order supply and while a significant amount will be delivered to customers beginning on Friday and throughout September, many iPhone pre-orders are scheduled to be delivered in October," Apple said in an official press statement, Monday.

Apple CEO Tim Cook reiterated the demand for the iPhone 6 and iPhone 6 Plus and said pre-orders for the two new phones set a record.

Apple also released the names of the next batch of countries where the new iPhones will debut starting Sept. 26. They include Austria, Belgium, Denmark, Finland, Ireland, Isle of Man, Italy, Liechtenstein, Luxembourg, Netherlands, New Zealand, Norway, Portugal, Qatar, Russia, Saudi Arabia, Spain, Sweden, Switzerland, Taiwan, Turkey and United Arab Emirates. China has not been given a release date, which is attributed to some regulatory approvals from the government.

As for this week's retail sale, Apple said, "Customers are encouraged to arrive early." The new iPhones will hit Apple retail stores in the U.S., Australia, Canada, France, Germany, Hong Kong, Japan, Puerto Rico, Singapore and the U.K. and also in carrier partner stores and authorized resellers.