The protracted absence on medical grounds of Nigeria's President Muhammadu Buhari has stoked fears of a full-blown political crisis at the heart of Africa's most populous nation.
The 74-year-old former army general left Abuja for London on January 19, leaving Vice-President Yemi Osinbajo in charge while he took time off.
But on the eve of his return earlier this month, it was announced that he was prolonging his stay to enable him to collect the results of unspecified medical tests.
Speculation, inevitably, went into over-drive that he may no longer be fit for the top job, and despite multiple claims he is well, the government has struggled to seize back the initiative.
For many, the situation revives memories of the situation seven years ago, when president Umaru Yar'Adua fell ill and later died while receiving treatment abroad.
It also once again lays bare the fragile divide between the majority Muslim north and the predominantly Christian south that characterises Nigeria and underpins political and daily life.
Succession to power at the federal level is seen as a balancing force between the two regions.
In 2010, it was the southern Christian former university professor Goodluck Jonathan who deputised for the northern Muslim Yar'Adua: now it is Osinbajo for Buhari.
When Yar'Adua died, his supporters prevented Jonathan from taking over. The argument ran that the north would be short-changed if a southerner was allowed to complete Yar'Adua's term of office.
It took a deft move by parliament to get Jonathan to assume power and prevent a major political melt-down.
Buhari has repeatedly had to deny opposition claims that he is seriously unwell with claims ranging from prostate cancer to kidney disease.
Jonathan's Peoples Democratic Party (PDP) even announced on its official Twitter account last year that he had died. The presidency said he had a persistent inner ear infection.
Conversation in Nigeria has in recent weeks has revolved around "what if?" scenarios: what if Buhari were unable to carry on? What if he were to die in office?
What if the north once again lost out on power to the south? How would it affect the choice of candidates for the next presidential elections in 2019?
Political analysts, however, dismiss the possibility of a re-run of the Yar'Adua/Jonathan scenario.
"There is a whole lot of difference between what happened during Yar'Adua's time and what is happening now," said Professor Abubakar Sadiq, from the Ahmadu Bello University in Zaria.
"There was a leadership vacuum under Yar'Adua because he did not hand over to his deputy... and a cabal bent on hijacking power prevented Jonathan from taking over," he told AFP.
Yar'Adua's illness was hidden from the public until he died and his body was brought back to Nigeria in the middle of the night, the political scientist noted.
"Nobody was allowed to see Umaru. But Buhari in his own case, handed over to his deputy. So, there is no way we will have a repeat of that ugly episode," he added.
Rotating power -- or "zoning" as it's called in Nigeria -- has long been assumed to be part of the constitution and at the heart of the Yar'Adua crisis.
But experts said it never has been and was only PDP policy.
Now Buhari's All Progressives Congress (APC) is in power, there is theoretically no reason why anyone of any ethnicity, religion or political affiliation can't be president.
Osinbajo, a trained lawyer who has long been in charge of economic policy, has widely been seen to be competent, travelling across the country and abroad, and chairing meetings.
"If the unexpected happens, Osinbajo should assume the full mantle of leadership," said Sadiq.
Politics lecturer Dapo Thomas, of Lagos state university, agreed there was no cause for concern and said the constitution was "very clear" on the succession, should it come to that.
"If the president cannot continue because of ill health, incapacitation or death, his vice will take over," he explained.
The slew of photographs in recent days of Buhari meeting delegations of well-wishers in London should go a long way to show he was not as ill as some have suggested, he added.
Buhari's illness had been politicised, he said, adding: "What is happening is dirty politics by mischief-makers... working to ensure that the government fails."
Buhari, who headed a military government in the 1980s, has been struggling to rid Nigeria of the endemic corruption that has blighted its development and plunged the country into recession.