The European Champions Cup semi-finals and final have been postponed by European Professional Club Rugby (EPCR) amid the coronavirus pandemic.
Matches at the same stages of the Challenge Cup have also been postponed.
The EPCR Board held a conference call on Monday to discuss the move and confirmed their decision on Tuesday.
They remain committed to completing the two competitions despite the COVID-19 outbreak, which has had a devastating impact on global sporting schedules.
But the 2020 finals in Marseille will not take place on May 22 and 23 as scheduled, while the semi-finals originally due to be held across May 1, 2 and 3 will also be moved.
The April quarter-finals had already been postponed and all three of the remaining rounds will be rescheduled in collaboration with the continent's major leagues.
"In making the decision, the board is abiding by the official directives and recommendations of the relevant authorities in its territories to restrict the COVID-19 pandemic," read the EPCR statement.
"In light of the earlier postponement of its quarter-final matches and with fixtures in Europe's professional league competitions currently suspended due to the public health crisis, EPCR believes it necessary to provide as much clarity as possible to all stakeholders regarding the knockout stages of its tournaments.
"To that end, EPCR is working with the leagues and unions to restructure a conclusion to its season as part of a wider rescheduling of the remainder of the season in Europe, with all contingencies underpinned by the requirement to protect the health and welfare of players, club staff, match officials, supporters and the wider rugby community.
"It is planned to reschedule the quarter-final and semi-final matches, as well as the Marseille finals, in line with fixtures in the professional league competitions, subject to advice from government and local authorities."
Fans will be entitled to a refund if they are unable to attend on the rearranged dates.