There’s been much written in the past couple of days about weakening demand for Apple’s iPhone 5 in the face of competition from Samsung, but according to UBS analyst Brent Thill, the iPad is putting a severe dent in Microsoft’s hopes for its Surface tablet range.

Thill had previously estimated that Microsoft would sell 2m Surface RT tablets in the fourth quarter, but in a note to investors, Thill downgraded his estimate to just 1m sales of the devices. That compares with an estimated 20m iPad sales in the same period.

Leaving the enduring appeal of the iPad out of the equation, Thill puts the problem partly down to distribution – for most of the fourth quarter, the Surface RT was available only in Microsoft’s own stories.

The news comes a few days after Samsung said it would not be releasing its Windows RT-powered ATIV tablet in the US market, claiming that the average US consumers does not understand the difference between the Windows RT (Runtime) and Windows 8 operating systems.