Vladimir Putin probably never thought he'd be celebrating his 70th birthday this way.
The Russian leader, who cut a ruthless path to power and changed the law so he could theoretically rule to the age of 84, is suddenly faltering.
His ruinous war in Ukraine is spiralling ever further from his control, prompting him to mobilise 300,000 reluctant reservists to the eastern front.
He also scrambled to illegally annex vast swathes of Ukrainian territory, even as his troops struggle to occupy much of it.
The man who dreamed of restoring the Russian empire to its former glory is presiding over a nation in isolation and an economy in shambles.
To add insult to injury, Russia watchers are now openly speculating about who would replace him if his position became untenable.
A post-Putin Russia, once an unthinkable proposition, now seems like a genuine possibility to some.
"If Putin is removed from power, self-preservation on the part of Russia's oligarchs, generals, and senior functionaries will be a primary driver," said Richard D. Hooker Jr, a nonresident senior fellow with the Atlantic Council.
"Because there is no obvious mechanism for a peaceful transition of power, there is potential for a power vacuum to develop in the event of Putin's ouster."
While Putin has deliberately avoided grooming a successor in recent years, there could be several Kremlin allies waiting in the wings for their opportunity.
As the Russian leader blows out the candles on his birthday cake tonight, these are the three men he should keep a watchful eye on.
The confidant, Dmitry Medvedev
There was a time when Dmitry Medvedev's future as Putin's successor was assured.
Like all those in the Kremlin inner circle, Medvedev hailed from Putin's hometown of St Petersburg.
He was also, it seems, happy to eternally remain the Robin to Putin's Batman.
"Putin liked Medvedev's lack of ambition," Russian journalist Mikhail Zygar wrote in his book All The Kremlin's Men.
With Putin then hamstrung by a constitutional two-term limit on the presidency, Medvedev acted as a seat warmer from 2008 to 2012.
The farce saw Putin act as prime minister, while almost certainly pulling the strings in the background.
The two men appeared in a series of photo opportunities together that tried to make the most of their bromance: they had breakfast together at Putin's summer home, they sipped hot cocoa after a day of skiing, and they went fishing in matching khaki outfits.
A US diplomatic cable released by WikiLeaks in 2010 included a joke that was making the rounds in Moscow at the time.
"Medvedev sits in the driver's seat of a new car, examines the inside, the instrument panel, and the pedals. He looks around, but the steering wheel is missing," then-US ambassador in Moscow, John Beyrle, wrote in his dispatch to Washington DC.
"He turns to Putin and asks: 'Vladimir Vladimirovich, where is the steering wheel?' Putin pulls a remote control out of his pocket and says: 'I'll be the one doing the driving'."
After four years, Medvedev stepped aside to allow Putin to return to the presidency and resumed his post as prime minister.
Their job-swapping arrangement might have lasted for years if Putin's government had not faltered, leaving the Russian autocrat in need of a convenient scapegoat.
From 2014, when the West imposed sanctions in response to Putin's illegal annexation of the Ukrainian territory of Crimea, Russia's economy began to stagnate.
Russians, struggling to survive with their low wages and tiny pensions, were starting to blame their ruler.
Medvedev did himself few favours when pensioners begged him for help during a 2016 trip to Crimea.
"There's no money, but hang in there. All the best!" he said before awkwardly scuttling away.
The following year, catastrophic allegations emerged that Medvedev was lining his own pockets as his people suffered.
The prime minister was accused of embezzling $1.2 billion to fund his mansions, yachts and a voracious online shopping habit.
While similar allegations have been made against Putin and many other members of his inner circle, the timing could not have been worse for the Kremlin.
In 2020, Medvedev was removed from his post and demoted to deputy head of the country's Security Council.
During Putin's disastrous invasion of Ukraine, Medvedev has reinvented himself as an anti-Western war hawk.
"I hate them. They are bastards and degenerates. They want us, Russia, to die. And while I'm still alive, I will do everything to make them disappear," he wrote on Telegram in August.
Whether his sabre-rattling puts him in the right position to succeed his former friend remains unclear.
But analysts say the tone of his rhetoric suggests he's signalling that he's up for the job if it becomes available.
"His over-the-top, hardline comments on foreign policy issues and insults hurled at Western leaders often look comical, but the role he's trying to play is clear," Andrei Pertsev, a political commentator at the Carnegie Endowment for International Peace, said in August.
"It blends tough isolationism with populism, firmly placing the blame for internal woes on the shoulders of external enemies."
The bodyguard, Alexei Dyumin
Given Putin's tendency towards machismo, it is perhaps fitting that a suitable replacement may be the man who claims to have once saved him from a brown bear.
Alexei Dyumin served as one of Putin's personal security officers from the moment he became acting prime minister in 1999.
According to the Organized Crime and Corruption Reporting Project, Dyumin has been handsomely rewarded for his loyalty over the years with some of Russia's most valuable land.
An investigation by Novaya Gazeta named Dyumin as one of three presidential bodyguards who accumulated millions of dollars' worth of property from a giant poultry plant outside Moscow that former workers say they were swindled out of in the 1990s.
For more than a decade, Dyumin guarded the Russian leader from potential threats — by his side as he met with leaders of state and Siberian tigers alike.
In 2012, then chief of the president's security detail, he came across an intruder at the official residence.
"We looked each other in the eyes, he stepped back a bit. I opened the door and unloaded the entire cartridge of my pistol under his legs," Dyumin recounted in an interview in 2016.
"I felt pity for the bear."
By 2013, Dyumin had made a meteoric rise through the ranks to become deputy chief of the military intelligence agency formerly known as the GRU.
Until then he had been best known as a burly man who followed the president around and was regularly spotted playing goalkeeper in Putin's beloved Night Hockey League.
But in his new post, Dyumin seemingly played a key role in Russia's activities in Ukraine.
According to Russian newspaper Kommersant, his team orchestrated the evacuation of Ukrainian president Viktor Yanukovych in 2014, following the Euromaidan uprising that saw him removed from his post.
Dyumin himself has denied any involvement with the evacuation mission, but he has been repeatedly credited with leading the military's Special Forces Operations — the so-called "little green men" — in Russia's annexation of Crimea.
Dyumin was bestowed with the highest honorary title, Hero of Russia, for his efforts, and was later promoted to Deputy Defence Minister under Sergey Shoygu.
In 2016, Putin found a new position for his longtime bodyguard, this time appointing him governor of Tula — a strategic region south of Moscow with which he held no apparent ties.
Ever since, Kremlin watchers have speculated whether this could be the relatively unknown newcomer primed to take over the leadership one day — just as the young Putin did for Boris Yeltsin.
"Dyumin will never question the Putin legacy nor let any harm come to Putin himself. Dyumin will be excellent as a president for the power elite," pro-Kremlin journalist Sergei Dorenko suggested in 2017.
The spymaster, Nikolai Patrushev
But the man who has recently emerged as the most likely contender bears a striking resemblance to Putin himself.
A spymaster and political operative who shares the president's contemptuous view of the West, Nikolai Patrushev has carved out a similar path to power.
Like Putin, Patrushev grew up in St Petersburg and joined the KGB as a young security officer in 1975.
After the Soviet Union collapsed, both men worked in the Yeltsin administration. He played second fiddle to Putin at the Federal Security Service (FSB), but when Putin became acting prime minister in 1999, Patrushev took his place.
Though observers have stopped short of describing the pair as friends, Putin spoke of a certain "comradeship" he felt with Patrushev in his 2000 autobiography.
Putin gave Patrushev, as head of the FSB, immense power to protect the stability of the Kremlin's rule.
To Patrushev, those who served in the nation's security services were an elite class — "the new nobility" of Russia.
In his powerful position he was accused of approving illegal operations, from deadly bombings in Chechnya to the assassination of Kremlin critic Alexander Litvinenko.
To this day, Patrushev has played an important role as a member of Putin's "siloviki" inner circle — the "men of force" from security, police and military backgrounds who now wield their power in the political sphere.
Since 2008, Patrushev has headed the Security Council of Russia, interpreting intelligence from its networks of spies and informants to formulate security policy and extending its reach into domestic and foreign affairs.
Patrushev has made his voice heard on the global stage, most recently flagging stronger ties with China as Russia's top policy goal, and warning Lithuania would suffer for cooperating with EU sanctions that put Russian enclave Kaliningrad at risk.
According to Mark Galeotti, from London-based security think tank the Royal United Services Institute, Patrushev is the most dangerous man in Russia, in a unique position to influence the president and "encourage an aggressive, adventurist agenda".
The two men share an ideology that paints the West as a threat to Russia's longevity, and Patrushev is among those who have most prominently and consistently circulated the narrative justifying Putin's invasion of Ukraine.
He has directly accused the United States of igniting tensions in eastern Ukraine, and lashed out over "the reckless expansion of NATO".
"Ukraine does not interest [the United States] at all. Their interest lies with Russia. They would much rather that Russia did not exist at all. As a country," he told The Guardian in 2015.
Former MI6 chief Sir Richard Dearlove believes Patrushev is the most likely heir should the Russian President fall suddenly ill within the next year.
But at 71, the spymaster would not solve the question of a longer term succession plan.
One school of thought suggests Patrushev could be grooming his 44-year-old princeling son, Dmitry Patrushev, to take over the reins.
Either Patrushev — or indeed anyone else who steps into the breach should Putin find himself out of a job — would inherit ultimate responsibility for the messy war that has gutted the Russian military and left an economy in tatters.
So will Vladimir Putin leave his post?
While Putin may be closer to the brink than ever before, it's not yet clear if a power transition in Russia is imminent.
The circumstances in which Putin leaves office and the person who rises to replace him may depend on many factors.
Whether it's a voluntary abdication, a medical emergency or a palace coup, a different contender emerges as the frontrunner.
Putin has also put in place many barriers to make it difficult for him to be removed without his consent.
He has a 50,000-strong security operation solely tasked with his protection called the Federal Protective Service.
A conspiracy to overthrow him would be extraordinarily tricky to arrange given the country's expansive surveillance apparatus.
But whatever happens next, Putin is running out of escape routes from his Ukrainian catastrophe.
His main foe, Ukrainian President Volodymyr Zelenskyy, now says he has no intention of negotiating a ceasefire with Putin.
"We will negotiate with the new president," he said.
