Nelson Mandela was back in hospital on Saturday in a "serious but stable" condition, triggering an outpouring of concern from around the world for the beloved South African hero.
Mandela, who turns 95 next month, was whisked to a Pretoria hospital in the early hours of Saturday with a renewed lung infection. It is his fourth hospital stay in seven months.
"The truth of the matter is a simple one. Madiba is a fighter and at his age as long as he is fighting, he'll be fine," presidency spokesman Mac Maharaj told AFP, using Mandela's clan name.
His wife Graca Machel was at his bedside in hospital after calling off a trip to London.
The anti-apartheid icon was once again suffering from pneumonia, after he was discharged in April for the same condition, said Maharaj.
"His condition deteriorated to the point where it was found necessary to hospitalize him," he said.
"But I am told by the doctors that he is breathing on his own, so I think that is a positive side," he added.
The announcement, calling his condition "serious", sparked a buzz on Twitter.
"Stay strong mr Mandela heaven isn't ready for you quite yet!," was one plea.
But there were also blunt calls to accept Mandela's increasing frailty and mortality.
"Gosh, Madiba gets no rest from the media. Let him die with dignity. It's not a circus folks," tweeted @Eish_Mag.
In his rural childhood village of Qunu, where Mandela once tended cattle, the news came via radio for Malunga Mbokodi.
"I was shocked to hear from the radio this morning that he was again in hospital," the 62-year-old told the Sapa news agency.
"I think, we should just accept it that Mandela is old and he will go soon," he added.
The ruling ANC called for people at home and abroad to keep "our beloved statesman and icon, Madiba" in their thoughts and prayers.
'Getting Too Frequent and Concerning'
The Nobel peace laureate is revered as a symbol of forgiveness after leading South Africa into multi-race democracy as its first black president after decades of apartheid rule.
"My thoughts are with Nelson Mandela, who is in hospital in South Africa," tweeted British Prime Minister David Cameron.
"Getting too frequent and concerning -- he is 94," tweeted Zwelinzima Vavi, general secretary of Cosatu, the powerful labour union allied to the ruling ANC.
Mandela was receiving care at his Johannesburg home when his lung problems returned.
He was diagnosed with early-stage tuberculosis in 1988 and also has had treatment for prostate cancer and suffered stomach ailments.
The government has not disclosed where he has been taken for treatment.