Since his transformation from political prisoner to leader of South Africa, the former has become one of the most respected men in the world, a symbol of the triumph of justice over oppression. President Suharto of Indonesia, by contrast, is a polar opposite: a stern autocrat and liberal bogeyman with a grim record of political oppression. But, against all expectations, the two have become correspondents. And hopes are rising that their unexpected entente could provide a solution to one of the most stubborn small wars in the world.
The conflict in question is that of East Timor, the former Portuguese colony invaded by Indonesia in 1976. Ever since its act of annexation the following year, Jakarta has refused to brook any compromise, and brutally crushed the dwindling East Timorese resistance.
United Nations-supervised talks between Indonesia and Portugal, which is still recognised in the UN as the administering power, have been deadlocked for years. But hesitantly - and despite a mortifying hiccup this week - things may at last be moving, thanks to the discreet personal intervention of the South African president.
With piquant symbolism, Mr Mandela is concentrating his diplomatic efforts on the fate of a celebrated political prisoner - Xanana Gusmao, the leader of the East Timorese resistance, who is serving a 20-year prison sentence. Last month, Mr Mandela made an official visit to Indonesia.
A week after his departure, to general astonishment, it emerged that he had requested and been allowed a meeting with Mr Gusmao, inside the grounds of President Suharto's palace.
"We can never normalise the situation until all the leaders, including Gusmao, are free," Mr Mandela said last week, after meeting in Pretoria with the Portuguese President, Jorge Sampaio.
He formally requested Mr Gusmao's release in a private letter to President Suharto which this week became the focus of a profound diplomatic embarrassment.
Instead of being delivered directly to Mr Suharto, it appears to have been delivered to the Portuguese embassy in Pretoria, which leaked it to journalists in Lisbon.
For this, the Portuguese ambassador has been expelled, though the bungle does not appear to have done lasting damage to the nascent negotiations.
Despite their contrasting backgrounds, Mr Mandela and President Suharto are said to have a warm personal relationship, based no doubt on Indonesia's support for the African National Congress during the apartheid period.
Both countries are former Dutch colonies, and leading members of the Non-Aligned Movement, the UN of the developing world.
But it is a measure of Mr Mandela's global standing that he is able to broach with President Suharto what is almost a taboo subject in Indonesian political circles.
The timing of the initiative also provides reasons for expectation. The stalled UN talks resumed this week, and there are rumours, so far denied, that the Secretary-General, Kofi Annan, will soon travel to Pretoria. On 17 August Indonesia celebrates Independence Day, a traditional time for the release of prisoners.
"If Bill Clinton had suggested this, he would probably have got a stiff response," said a diplomat in Jakarta.
"But next to Mother Teresa, it's hard for them to know what to do with Mandela. He's got such broad clout, particularly in the Third World.
"It's pressure on the Indonesians but it also gives them a kind of cover to solve this problem without losing so much face."Reuse content