An employee carries a stack of new Apple iPad Air tablets inside the Apple Store on New York's fifth avenue after the new iPad went on sale Friday, Nov. 1, 2013. Reuters

With Apple’s (NASDAQ:AAPL) latest fifth-generation iPad Air likely to enjoy solid sales, and the yet-to-be-released Retina iPad mini expected to follow suit, the company’s overall tablet shipment is predicted to see a jump of about 4 million to 6 million units in the fourth quarter, compared to the previous quarter this year.

Citing “sources with Taiwan's supply chain,” DigiTimes reported on Tuesday that Apple’s worldwide iPad shipments could reach 18 million to 20 million units in the fourth quarter of 2013, accounting for a 42 percent jump over the 14.1 million iPads shipped in the third quarter of this year. According to the report, Apple shipped 48.2 million iPads in the first three quarters of 2013, and with the expected fourth-quarter shipments, the company may ship a total of 66.2 million to 68.2 million iPads worldwide in 2013.

Although the numbers look impressive, the report stated that they would represent a mere 4 percent growth over 2012's volumes -- the lowest year-on-year growth among “first-tier tablet vendors.”

And, if the estimate proves to be accurate, Apple’s 2013 iPad growth rate will also lag behind the tablet market's overall annual growth of 50 percent in this year. The global tablet market is expected to see annual shipments rise from 140 million in 2012 to 220 million in 2013, according to DigiTimes.

Last week, Piper Jaffray's Gene Munster estimated that Apple could sell between 2.5 million and 3.5 million iPad Air units over the first weekend, besting the 3 million mark the company reached over the same period in 2012.

Meanwhile, a report from International Data Corporation, or IDC, that was released last week showed that Apple’s share in the worldwide tablet market plunged to its lowest point in the third quarter of 2013, dropping 11 percent from the same period last year. According to IDC, Apple’s market share in tablets dropped to 29.6 percent in the third quarter from 40.2 percent during the same period last year.

However, IDC expects the company to regain momentum in the fourth quarter when the new iPad Air and the Retina iPad mini would both be out in the market.

“With two 7.9-inch models starting at $299 and $399, and two 9.7-inch models starting at $399 and $499, Apple is taking steps to appeal to multiple segments,” Jitesh Ubrani, research analyst at IDC, said in a statement. “While some undoubtedly hoped for more aggressive pricing from Apple, the current prices clearly reflect Apple's ongoing strategy to maintain its premium status.”