Paying tribute to his personal hero, US President Barack Obama met privately with Nelson Mandela's family as the world anxiously awaited news on the condition of the 94-year-old anti-apartheid leader.
The meeting on Saturday took place at the Nelson Mandela Foundation, hours after the president said he was not angling for a "photo op" with the ailing former South African leader.
Obama praised Mandela's "moral courage" during remarks from the grand Union Buildings, Johannesburg, where Madiba, as he is called in South Africa, was inaugurated as his nation's first black president.
Obama also called on the continent's leaders, including in neighboring Zimbabwe, to take stock of Mandela's willingness to put country before self and step down after one term despite his immense popularity.
"Our thoughts, and those of Americans, and people all around the world are with Nelson Mandela and his family," said Obama.
"The triumph of Mandela speaks to something deep in human spirit; a yearning for justice and dignity which transcends ... bounds of race."
"We as leaders occupy these spaces temporarily and we don't get so deluded that we think the fate of our country doesn't depend on how long we stay in office,'' Obama said during a news conference with South African counterpart, Jacob Zuma.
Mandela remains in a critical condition in hospital in Pretoria with a lung infection.
Obama also said he was pleased to be able to take his daughters to Robben Island, where Nelson Mandela was jailed for 18 of his 27 years' imprisonment under white apartheid rule.
On Africa, he said he firmly believed that "all too often, attention is paid to Africa when there's a crisis" despite positive developments on the continent.
Elsewhere, the presidents talked about boosting bilateral trade, recognising Africa's potential as a continent with some of the world's fastest-growing economies and increasing the presence of African nations on the global political sphere.
"Africa must be part of globalisation ... We are part of events that change the world," said Zuma.
The two leaders met about a 10-minute drive from the Pretoria hospital where 94-year-old Mandela lies in critical condition.
Mandela's health is said to be improving after several difficult days.
Reporting from outside the hospital, where people are gathered to pray and offer tributes for Mandela, Al Jazeera's Peter Greste said: "The mood here has been a little bit more upbeat over the past 24 hours."
Mandela, who became South Africa's first black president after being jailed for 27 years for opposing white minority rule, is suffering from a recurrent lung infection and has been hospitalised three times since last December.
The illness dates back to his years in apartheid-era prisons.
After taking a turn for the worse last weekend, Mandela, who will turn 95 next month, has since shown tentative signs of recovery.
"From what he was a few days ago, there is great improvement, but clinically he is still unwell," said ex-wife Winnie Madikizela-Mandela, who has visited him regularly in hospital.
I do not need a photo op. The last thing I want to do is to be in any way obtrusive
She called on the media not to "get carried away" in their reporting on her former husband's illness, but thanked them for their support.
"Please understand the sensitivities and the feeling of the family," added the MP, who tirelessly campaigned for Mandela's release during his imprisonment under apartheid.
"We had no idea of the love out there for us in our particular situation and if sometimes we sound bitter it is because we are dealing with a very difficult situation," she added.
Mandela's plight has lent a deeply poignant tone to Obama's three-day stay, part of his second extended tour of Africa that will end in Tanzania.
Speaking in Senegal, where he began his trip, Obama described Mandela as "a personal hero".
When they first met in Washington in 2005, Obama was a newly elected senator for Illinois, and the two have spoken several times since by telephone.
But there has been no face-to-face meeting between them since Obama was elected in 2008.