A QA tester for Traveller's Tales Games tweeted an image of a revised Wii U tablet controller, complete with a number of minor alterations, reports Games Radar.
The new controller replaces the original's analogue circle pads with actual sticks, while the start and select buttons now appear on the right side of the device.
It also features actual Wii U branding, quashing rumors that Nintendo would rebrand the console prior to its launch.
Whether the revised controller is a development model or the final design remains unclear. Nintendo is yet to comment and the image has since been removed from Twitter.
Nintendo will unveil the console's final hardware and specifications at this year's E3 event in Los Angeles, where the device will be present and playable.
The old controller (left) and new controller (right)
Its initial launch lineup of games will also be revealed. It is said to include Pikmin 3, Rayman Legends and the new Wii U Super Mario game.
Nintendo will wait until after E3 to announce release dates and pricing details, although the console is expected to launch by the year's end.
Watch the Wii U concept trailer below: