Russian President Vladimir Putin is to be guest of honour at a military parade in the Serbian capital Belgrade that is loaded with symbolism, reports GHN based on BBC.
It marks 70 years since Soviet troops helped liberate the city from Nazi occupation and is the first to be held in nearly 30 years.
Serbia's historic ties with Russia sit awkwardly with its EU ambitions, especially since the Ukraine crisis.
On the eve of his arrival, Mr Putin accused the US of "hostility".
In an interview with Serbian newspaper Politika, he accused America of trying to blackmail Russia with sanctions over Ukraine but warned that would be futile.
He is due to meet a number of foreign leaders at an Asia-Europe summit in the Italian city of Milan later on Thursday.
They include Ukrainian President Petro Poroshenko and German Chancellor Angela Merkel, amid pressure on Russia to implement a peace plan for eastern Ukraine.
Under sanctions - and increasingly isolated over his actions in Ukraine - President Putin remains outwardly defiant, the BBC's Sarah Rainsford reports from Moscow.
One of the key issues that Mr Putin is set to discuss with his Ukrainian counterpart is a possible deal for Ukraine to pay its gas debts in return for a resumption of Russian gas supplies.
