Dakar - US President Barack Obama flew from Senegal to South Africa on Friday, in an Africa trip largely overshadowed by the fading health of the anti-apartheid icon.
Obama spent three days in Dakar talking up African democracy and paying a poignant visit to Goree Island, a potent symbol of the slave trade, on the first leg of a three-nation tour of the continent which will also take in Tanzania.
Mandela's ill health means the two men, who shattered racial boundaries on either side of the Atlantic, will not hold a long-anticipated meeting for the cameras.
Mandela, who turns 95 next month, was rushed to hospital three weeks ago with a recurrent lung infection.
On the eve of Obama's visit, Madiba was said to be in a critical condition, but had stabilised since a scare forced President Jacob Zuma to cancel a trip to neighbouring Mozambique.