London - Wales will face Australia and South Africa during their last November international series ahead of the 2019 World Cup in Japan, the Welsh Rugby Union (WRU) announced on Monday.
Warren Gatland's side will start the series against Scotland on November 3, before facing the Wallabies, Tonga and the Springboks on the following three Saturdays that month.
The Scotland clash is a surprise as it is rare for Europe's leading sides to play each other outside of the Six Nations, the World Cup and World Cup warm-ups.
Scotland will be the first major northern hemisphere side to come to Cardiff in the autumn since a four-match end-of-year campaign became a standard feature of Wales' international programme in 2001.
November's match between the Celtic nations will be played for the 'Doddie Weir Cup', with the fixture raising money for the charity set up by the former Scotland lock, who is suffering from Motor Neurone Disease.
"First and foremost we have an impressive fixture list for the Under Armour Series this autumn, one that will challenge Warren and his team and provide ideal preparation for the following Six Nations Championship and the 2019 Rugby World Cup thereafter, and also some fascinating contests to capture the imaginations of the rugby loving public in Wales," said WRU chief executive Martyn Phillips.
Wales won 34-7 at home to Scotland in February during a Six Nations where they finished runners-up to Ireland.
But in the 10 years since Gatland has been their head coach, Wales have recorded just four wins from 38 Tests against the southern hemisphere 'Big Three' of South Africa, New Zealand and Australia.
Three of those victories have come against the Springboks, with a solitary win over the Wallabies back in 2008.
Wales haven't beaten Gatland's native New Zealand since 1953, though.
2018 UNDER ARMOUR SERIES
(Kick-off times to be confirmed)
Saturday, November 3 - Wales v Scotland
Saturday, November 10 - Wales v Australia
Saturday, November 17 - Wales v Tonga
Saturday, November 24 - Wales v South Africa