Nelson Mandela was comfortable and breathing without difficulty after being treated for pneumonia, the presidency said on Saturday as the anti-apartheid icon spent a third day in hospital.
Messages of concern for the ailing 94-year-old, one of the towering figures of modern history, have poured in since his admission late Wednesday for what was confirmed as "a recurrence of pneumonia".
Mandela had a build-up of fluid which had developed from the lung infection, known as a pleural effusion or "water on the lungs", drained from his chest.
"This has resulted in him now being able to breathe without difficulty," said Zuma's office said in a statement.
"He continues to respond to treatment and is comfortable."
On Friday, Mandela was said to be in good spirits and making steady progress.
"He sat up and had his breakfast in bed," Zuma's spokesman Mac Maharaj, who was jailed with Mandela during apartheid, told AFP.
There were no details on Saturday on how long he would remain at the undisclosed hospital.
Mandela's recent health troubles have triggered an outpouring of prayers but have also seen South Africans come to terms with the mortality of the revered Nobel Peace Prize winner.
The former president is idolised in his home nation, where he is seen as the architect of South Africa's peaceful transition from white minority-ruled police state to hope-filled democracy.
Nearly 20 years after he came to power in 1994, he remains a unifying symbol in a country still riven by racial tensions and deep inequality.
It is the second time this month that he has been admitted to hospital, after spending a night for check-ups on March 9.
That followed a nearly three-week hospital stay in December, when Mandela was treated for another lung infection and underwent gallstone surgery.
He was diagnosed with early-stage tuberculosis in 1988 during his 27 years in prison under the apartheid regime and has long had problems with his lungs. He has also had treatment for prostate cancer and has suffered stomach ailments.
Officials said doctors' reports of Mandela's steady progress should be taken in context.
"Yes, indeed it is good news but we need to be cautious, bear in mind his age," said Maharaj, who was a political prisoner with Mandela at Robben Island jail off the coast of Cape Town, on Friday.
'We want him back, even though he's an old man'
While Mandela's legacy continues to loom large over South African politics, he has long since exited the political stage and for the large young population he is a figure from another era, serving as president for just one term.
He has not appeared in public since South Africa's football World Cup final in 2010.
Labour unrest, high-profile crimes, grinding poverty and corruption scandals have effectively ended the honeymoon enjoyed after Mandela ushered in the "Rainbow Nation" but his decades-long struggle against apartheid resonates.
"The whole country is not happy about the old man's health, he is not so well, but we wish him a speedy recovery," Soweto handicraft seller Nhlanhla Ngobese told AFP on Saturday.
"We want him back, even though he's an old man, he's an icon to us, a hero to us, we still want his diplomacy."
The name and location of the hospital where Mandela is being treated have not been disclosed to allow his medical team to focus on their work and to shield the family from the intense media interest.
In the past he has been hospitalised at a clinic in Pretoria.
Away from the public eye, Mandela has grown increasingly frail.
His December hospital stay was his longest since he walked free from jail in 1990.
English Premier League football club Sunderland is calling its clash Saturday with Manchester United "Nelson Mandela Day", in honour of the club's association with Mandela's charitable foundation.