Super Rugby franchise the Western Force will not be part of next year's competition.
The Australian Rugby Union (ARU) announced it has decided to discontinue a Super Rugby licence for the Perth-based outfit.
The competition is being reduced from 18 teams to 15 in 2018, with the Force joining South African sides the Cheetahs and Southern Kings in being cut, although Force chiefs are now likely to launch a legal battle.
The Cheetahs and Southern Kings have since become part of an expanded Guinness PRO14, and will play their opening games in three weeks.
ARU chairman Cameron Clyne described the Force's demise as "a sad day for rugby".
In a statement, Clyne said: "This has been a complex process to reduce Australia's Super Rugby representation to four teams, as agreed by SANZAAR (South Africa, New Zealand, Australia and Argentina Rugby) following its review of the competition.
"We are regretful that this issue has consumed so much of the public commentary on the game in 2017.
"It was clearly not our intention for this to play out over such a lengthy period, however, there have been factors outside the ARU's control that have prevented us from completing the process.
"Our decision to exit the Western Force has been guided primarily by financial outcomes.
"As we have reinforced throughout this process, there are commercial realities which are linked to declining on-field performance across our Super Rugby teams which has put Australian Rugby in a position where it can no longer sustain five teams.
"This is a sad day for rugby, especially for Western Force fans. We accept that there will be anger and resentment over this decision, and we sympathise with those fans. We sincerely hope that they are not lost to the game forever.
"The decision to exit the Western Force from Super Rugby is not a decision to abandon the game in Western Australia.
"Western Australia will retain an important place in Australian rugby, and the ARU will continue to support youth development programs and the community game in the west. There will be a clear pathway for young Western Australian rugby players to reach the highest level and represent the Wallabies.
"Our immediate concern is to support the individuals at the Western Force through these difficult circumstances, and we will deploy various ARU management staff to Western Australia to provide assistance to all players and staff."
The Force made a Super Rugby debut in 2006, while their ex-players include former Australian Test stars Matt Giteau, Nathan Sharpe and James O'Connor.