He, Boris not Bill, was supposed to be the invalid, the ailing leader who could barely walk. He was the one whom we all felt sure was doomed by ill-health to leave office soon, ending a political odyssey that has embraced the collapse of the Soviet Union, economic reforms, a slump comparable with America's Great Depression, the bombardment of parliament, and a hugely costly war. And yet the lame one will be the accident-prone Bill Clinton, nursing a leg injured outside the golfer Greg Norman's house in Florida. If all goes smoothly, Mr Yeltsin will have once again proved not only to have astounding powers of recovery, but staggeringly good fortune.
He needs it. He will arrive in Helsinki today looking much like an ageing boxer who is fighting out of his class, and is therefore reduced to weigh- in vaunts. The main issue at hand, Nato enlargement, concerns no less momentous a theme than the security of Europe in the next century, yet the advantage clearly lies with his opponent. So much so that Andrei Kozyrev, his former foreign secretary, has suggested that the summit is a mistake. "What kind of diplomacy is it that makes our president go to the worst possible meeting with a US president after six years of Russia's new existence?" he asked Echo Moskvy radio station. "Now Yeltsin has either to retreat before the enemy or enter a new tough round of confrontation."
Mr Yeltsin's last meeting with Mr Clinton was nearly a year ago, last April, when the G7 convened in Moscow. How times have changed. The conflict in Chechnya was still raging, despite Mr Yeltsin's insistence to the contrary. The Communists were riding high after securing 23 per cent in December's parliamentary election, and there was real concern - even among the cooler heads of western diplomats - that their leader, Gennady Zyuganov, would win the presidential election.
But time and again, Mr Yeltsin has proved it is dangerous to underestimate him. His flair for campaigning, the might and money of his election machine, and his capacity for "realpolitik" came to the rescue. He lavished wild promises on the electorate, squeezed Mr Zyuganov off the airwaves, and successfully wooed the support of a fellow candidate, the popular ex-paratrooper Alexander Lebed - who brought with him a healthy number of votes. Mr Yeltsin even managed to wind down and later end the Chechen war.
All this won him back his place in the Kremlin, but precious little else. Even before July's final round, he was crippled by hushed-up heart problems, beginning a period of absenteeism that has consumed a fifth of his four- year second term. Unstable and bewildered, the country was quietly run from behind the scenes by his then chief-of-staff, Anatoly Chubais, advised by the president's daughter, Tatyana, and a small group of business moguls.
Eight months on, the picture looks no better. This week's cabinet reshuffle, which has given a starring role to two young warriors of free market reforms, Mr Chubais and Boris Nemtsov, the 37-year-old governor of Nizhny Novgorod, has delighted the West - and particularly Mr Clinton. "It is a very positive sign," said US State Department's Nick Burns. "We are very anxious to work with that team."
But this enthusiasm is not shared by many Russians. The country is engulfed by deep disillusion, fostered by a welter of crises - from corruption reaching to the pinnacle of government, a collapsing welfare system and growing unemployment, to an army that is falling apart. Although inflation appears under control, consumer prices have risen by 1,700 times in the past five years, demolishing the life savings of most Russians. An epidemic of tax evasion has forced the government to slash back spending, stoking up vast wage and pension arrears. This hostile environment has prompted many to conclude that politics is nothing more than a dangerous contest between former Communist apparatchiki and mighty industrial and financial interests over the spoils of a wrecked land.
So the events of the next two days are crucial. Mr Yeltsin needs a public relations success to ease domestic tensions, and to prove to Russia that it is still a powerful player on the world stage. This will not be easy. No one expects a final settlement over Nato, although there may be some progress. Whatever deal eventually emerges, there will be few cheers in Russia; it remains as unshakeably opposed to the alliance's enlargement as the West is to forging ahead.
He may be able to notch up some modest gains elsewhere - movement over Russia's ambition to join the G7 and the World Trade Organisation, progress with the Conventional Forces in Europe Treaty and promises of US investment in return for a Russian pledge to create a more secure business environment. For the cameras, there will be some silver-tongued assurances from Bill, and some growling from Boris.
Mr Yeltsin is a great performer. The world will never forget how he climbed on to a tank to face down plotters in the abortive coup of 1991. He has a record for making astonishing come-backs - ranging from his return after being purged from the Soviet politburo in 1989 to his victory last year. But he will need all his Houdini-esque skills if he is to walk away from Helsinki without looking as lame as his American opponent.