Rugby World Cup organisers have been given another month to make a decision on whether the Olympic Stadium in London is to be one of the venues for the 2015 tournament.
England Rugby 2015 had expected to agree a final list of venues with the International Rugby Board on Friday but have secured an extension.
West Ham are preferred tenants to take over the Olympic Stadium but a final deal with the London Legacy Development Corporation has still to be agreed by the Premier League club.
That uncertainty has prevented tournament organisers from making a decision but they are keen to include the stadium if possible.
A RWC statement said: "Both parties agreed that appropriate time should be given to allow every possible opportunity to include the Olympic Stadium, one of the world's most recognisable venues.
"The additional time will enable England Rugby 2015 to finalise negotiations and scheduling with other venues."
England Rugby 2015 chief executive Debbie Jevans said: "We are determined to select the best venues and deliver the optimum schedule for the Rugby World Cup, and are delighted to have received such strong support from the RWC Limited board for our proposals.
"Our plans are on track and we are confident that we will finalise the schedule and the venues in the next few weeks."