His family names means "tough, like a walnut" and he will need to draw on all his robustness if he is to fulfil the prediction of a string of opinion polls and beat Yugoslav President Slobodan Milosevic. According to the polls, Vojislav Kostunica, a Belgrade lawyer and intellectual, who heads one of the smaller parties in Serbia, could oust Mr Milosevic in presidential elections on September 24th.
Eighteen opposition leaders joined together this month to back him after market research showed he was the most electable candidate, far more popular than more notable Serbian politicians, such as Vuk Draskovic and Zoran Djindjic. So now the all eyes are upon this 56-year-old lawyer and anti-communist dissident, a figure barely known in the West but with the potential to turn the tide of history.
The most recent opinion polls show Mr Kostunica with 35 per cent of the vote, Mr Milosevic with 23 per cent and several other parties trailing behind. Mr Draskovic's Serbian Renewal Movement, which refused to back Mr Kostunica, now sees its candidate polling just 5 per cent.
If no one wins more than 50 per cent in the first round, the election will go to a second round and, on present results, that should see Mr Kostunica head-to-head against President Milosevic.
So who is this surprise challenger? The man who could end the Milosevic decade traces his ancestry to a hamlet called Kostunici in central Serbia, not far from the city of Cacak. This region of Serbia lies in the shadow of a mountain called Ravna Gora and is the heart of historic Serbian nationalism.
Two Serbian uprisings against the Ottoman empire began here, so Mr Kostunica's family roots, together with his carefully moderated nationalist rhetoric, have won him a place in the proud hearts of many Serbs who are not drawn to other pro-Western opposition leaders.
Is he a nationlist? Mr Kostunica watches his words carefully. "I'm a normal, moderate, general nationalist in the same way as politicians in Great Britain, France and elsewhere," he says.
A long-time colleague, Dr Svetozar Stojanovic, says Mr Kostunica is a man "who is serious about democracy, but he is also serious about national interests. We also have our national interests. Let's look at them".
Vojislav Kostunica was born into an intellectual Belgrade family, the only son of a lawyer who was removed from the Serbian Supreme Court in 1946 for failing to comply with Communist justice. He soon began to follow the family record of dissidence. He studied law in Belgrade, then gained a Master's degree with a thesis on Political Theory and Practice of the Constitutional Courts in Yugoslavia. He then took a doctorate, which was a study of the political opposition in capitalist systems - and his thesis formed the basis for his first book.
He began teaching at the university, but was expelled in 1974 for giving his support to critics of President Tito's new Yugoslav constitution. This constitution decentralised Yugoslavia and Serbia - and many nationalists saw it as the beginning of the end of the Yugoslav federation.
Mr Kostunica continued his work in non-government institutes and, in 1983, caused a big stir among Yugoslavia's elite with a book that examined multi-party and single-party electoral systems.
He gained renown as a lawyer and human rights activist, working during the 1980s with the Committee for the Defence of Thoughts and Freedom of Speech. His clients included the Serbian vice-president and extreme right-winger Vojislav Seselj; Bosnian Muslim leader Alija Izetbegovic; and former Croatian President Franjo Tudjman.
In the same year that the Berlin Wall fell and communism across the East began to collapse, he jointly founded the Democratic Party - Yugoslavia's first alternative party to communism since the war. In 1990, he became an MP in the Serbian parliament and, two years later, split to form his own Democratic Party of Serbia.
Mr Kostunica sees the forthcoming elections as a defining moment: "It is a matter of life and death. These are not some sort of genuine elections. We are having a referendum on Milosevic."
Can he win? "I'm rather an acceptable person for many opposition groups and a large part of public opinion here. And I was rather tolerant towards those people who were supporting Milosevic and voting for him and we must get new votes. So I think there is a chance in these elections. There is reason for optimism," he says.
He has used some salty words against the US: "It takes a great deal of arrogance to say that promoting democracy in Yugoslavia is a long-term US goal. Democracy in Serbia is Serbia's goal and no one else in entitled to it. The real US goal is obviously a further break-up of Yugoslavia," he said recently.
He insists that he is not anti-American but blames Washington for sanctions which he says have "helped Milosevic to survive" and also for "NATO's aggression and bombing of Yugoslavia", which he says "helped Milosevic and hurt the common people".
He also blames the US for ignoring all other voices in Serbia for years and only dealing with Mr Milosevic.
Like many Serbs, he is ambivalent about the Hague war crimes tribunal: "I criticise all kinds of crimes committed by Serbs and non-Serbs," he says. "But there are many problems about The Hague. Being a lawyer, I think there is too much politics and not enough law in the Hague tribunal. I think it became political the moment the indictment against Milosevic was raised."