Nelson Mandela entered a seventh week in hospital on Friday, the day after his 95th birthday was marked by millions of people around the world, heartened by news that the anti-apartheid icon is showing signs of improvement.
Ndileka Mandela told AFP on Thursday that her grandfather is "steadily improving" and "using his eyes, nodding."
That message was echoed by President Jacob Zuma who said after visiting his predecessor's Pretoria bedside he "found him really stable and I was able to say 'happy birthday' and he was able to smile."
That is a dramatic turnaround for the ailing peace icon, who just weeks ago was thought to be close to death.
Mandela was rushed to hospital on June 8 with a recurring lung infection that had already put him in hospital three times in less than a year.
Outside the Pretoria facility which has been the focal point of a national vigil for the last 41 days, there were joyous scenes.
Revellers sang anti-apartheid struggle songs, as school children read poems dedicated to a man nearing the end of his long walk that took him from political prisoner to South Africa's first black president.
"Tata (father) Mandela has once again proved that he is a fighter," said well-wisher Agnes Shilowane, a local university student.
Thursday's news was a relief elsewhere in the country to South Africans who marked Mandela Day with a panoply of good deeds.
Biker gangs cleaned streets, volunteers painted schools and politicians spent 67 minutes on worthy projects -- all to mark Mandela's 67 years of public service.
Near Pretoria, Zuma tried to channel Mandela's cross-community appeal by delivering government housing to poor whites.
Messages of support also poured in from around the world -- and even from astronauts on the International Space Station -- to mark the anniversary, which many feared Mandela would not live to see.
US President Barack Obama -- who was unable to visit Mandela during a trip to South Africa last month -- led tributes to the peace icon, calling on people to honour him through volunteer work.
"Our family was deeply moved by our visit to Madiba's former cell on Robben Island during our recent trip," Obama said in a statement.
"We will forever draw strength and inspiration from his extraordinary example of moral courage, kindness, and humility."
In New York, Mandela Day was marked by the showing on giant screens in Times Square of "The Power of Words", a short film based on excerpts from his most memorable speeches.
Other well-wishers included the Dalai Lama, former US president Bill Clinton and his wife Hillary, US actor Morgan Freeman and Mandela's former jailer FW de Klerk, who went on to share the Nobel Peace Prize with him.
"Mandela's place in South Africa's history is assured," former president De Klerk said in a statement.
"His legacy of courage, perseverance and magnanimity will continue to inspire us -- and people throughout the world -- for generations to come."
The Mandela family also did their bit, with his grandchildren volunteering at a children's home.
They then gathered at the hospital for lunch, along with Mandela's third wife Graca Machel, who also celebrated 15 years of marriage to her husband on Thursday.
"The 67 minutes was the highlight of our day and also the time we spent with grandad and family. It was really a phenomenal day," Mandela's granddaughter Ndileka told AFP.
He was "excited" to have the family, including at least four great-grandchildren, gather around him for his birthday. "He always does, especially when he sees the little ones. It was good for him," said Ndileka.
The birthday meal included Mandela's favourite food, including "oxtail, prawns, dumplings and vegetables".
Another granddaughter, Zaziwe Dlamini-Manaway, distributed food at a school.
"I think it's important for us to give back," she said.
"We are a family, we hope for him to come home, and we know the whole nation would hope the same thing, and the whole world."
The United Nations declared the Nobel Peace laureate's birthday Mandela Day in 2010, but for many this year it takes on extra poignancy.
Clinton, UN leader Ban Ki-moon and Andrew Mlangeni, who was a prisoner with Mandela, honoured the legendary freedom fighter in a special ceremony at the UN headquarters.
In central Lisbon the Don Pedro IV Square was to be renamed Nelson Mandela Square, and an open-air Mandela-themed opera concert was planned in Paris.
On Saturday, the Australian city of Melbourne will hold a concert featuring local and African artists.
Born on July 18, 1918, Mandela fought against white rule in South Africa as a young lawyer and was convicted of treason in 1964.
He spent the next 27 years in jail.
It was in part through his willingness to forgive his white jailers that Mandela made his indelible mark on history.
After negotiating an end to apartheid, he became South Africa's first black president, drawing a line under centuries of colonial and racist suppression.
He then led reconciliation in the deeply divided country.
But the sunset of Mandela's life has been somewhat eclipsed by bitter infighting among his relatives.
A row over his final resting place has seen three of his children's graves dug up and their remains moved amid public brawling and legal action among his children and grandchildren.
People pose for a picture near a portrait of former South African president Nelson Mandela on July 18, 2013 outside the Medi Clinic Heart Hospital in Pretoria. Mandela entered a seventh week in hospital on Friday, the day after his 95th birthday was marked by millions of people around the world, heartened by news that the anti-apartheid icon is showing signs of improvement.
Chronology of the life of former South African president Nelson Mandela who turns 95 on Thursday.
The Eiffel Tower in Paris is floodlit in the colours of the South African flag on July 18, 2013 in honour of Mandela Day. Nelson Mandela entered a seventh week in hospital on Friday, the day after his 95th birthday was marked by millions of people around the world, heartened by news that the anti-apartheid icon is showing signs of improvement
A boy looks at a picture of former South African president Nelson Mandela during an event to mark Mandela Day in Mexico City on July 18, 2013. Mandela entered a seventh week in hospital on Friday, the day after his 95th birthday was marked by millions of people around the world, heartened by news that the anti-apartheid icon is showing signs of improvement.