US President Barack Obama has arrived in South Africa to pay homage to his hero Nelson Mandela, who was said to be showing "great improvement" in hospital.
Mandela's improving health after several difficult days raised the possibility of a meeting between the two men, who shattered racial boundaries on either side of the Atlantic.
Before he touched down in Pretoria late on Friday, Obama indicated he would defer to Mandela's family about whether to visit the ailing anti-apartheid icon.
"I do not need a photo op. The last thing I want to do is to be in any way obtrusive," Obama said aboard Air Force One.
"I think that the message we'll want to deliver is not directly to him but to his family, is simply profound gratitude for his leadership all these years," he added.
Mandela, who turns 95 next month, has been in intensive care for three weeks for a recurrent lung disease dating from his years in apartheid-era prisons.
After taking a turn for the worse last weekend, he 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 thanks 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 27-year 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 a three-nation Africa tour.
A visit by Obama to Mandela's former jail cell on Robben Island, off Cape Town on Sunday in particular is expected to be laden with symbolism.
Speaking in Senegal on the first leg of his long-awaited African trip, Obama described Mandela as "a personal hero".
The men met in 2005, when the former South African president was in Washington, and Obama was a newly elected senator, 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.