New Zealand Maori have enjoyed wins over the Lions, Fiji and Samoa
South Africa's proposed Lions warm-up match against New Zealand Maori in Soweto is in doubt because the Maori team is selected on racial grounds.
The match is scheduled to take place in June, before the British & Irish Lions arrive for their three-Test tour.
However, the South African national side is prohibited from playing against racially selected teams.
The rule is a "fundamental stumbling block" to the match taking place," said the South African Rugby Union (SARU).
"There are several obstacles to overcome should we wish to pursue the offer," added SARU's Andy Colquhoun.
"They include the financial viability of the project, logistics around venues and player availability and the fundamental stumbling block of a long-established President's Council resolution forbidding the appearance of SARU teams against opponents selected along racial lines.
"A final decision is not expected until the end of March."
New Zealand Rugby Union's Neil Sorenson responded: "Obviously, it would be fantastic for New Zealand Maori, the Springboks and their respective fans if the match took place.
"But it is still early days and we know that there are number of hurdles that need to be cleared if the match is to be confirmed."
The Lions' 10-match tour of South Africa is due to last from 30 May until 4 July and includes three Tests against the world champion Springboks.