Global celebrations and charity events will mark Nelson Mandela's 95th birthday, but the critically ill anti-apartheid hero may still be confined to his Pretoria hospital bed on life-support.
Volunteers will spend 67 minutes on Thursday on hundreds of community upliftment projects - a minute for every year of his activism.
But his hospitalisation for a recurring lung infection and bitter infighting among his relatives have tempered the festive spirit.
The United Nations in 2010 declared the Nobel peace laureate's birthday Mandela Day - to encourage people across the world to do just over an hour of good deeds.
Global celebrities have supported the campaign in memory of Mandela's 67 years of political activism.
"I will also be giving my 67 minutes to make the world a better place, one small step at a time," British business magnate Richard Branson pledged in a recorded message.
On Thursday, children in schools around South Africa will start their classes singing Happy Birthday to the former statesman. Celebrities have committed to painting schools, handing out clothes to impoverished children, and countless similar projects.
The inauguration of the Nelson Mandela Legacy Bridge is scheduled at the icon's birth village, Mvezo, in the rural Eastern Cape province.
A science-specialisation high school bearing his name is also due to be opened.
In the US, meanwhile, 17 cities have planned various activities on Thursday.
On Saturday, Melbourne will hold a concert featuring local and African artists, while a music festival later this year in Norway will promote equality in schools.
But the ailing icon is bound to spend his birthday in the hospital where he has been for the past six weeks, breathing with the help of a machine.
Almost a month ago, the presidency announced that his condition had worsened. But it has denied he is in a "vegetative state", as his family claimed in court documents dated June 26.
His health has recently improved, according to official statements and comments from family and friends.
His successor as president, Thabo Mbeki, even suggested he might be discharged from hospital in time to spend his birthday at home.
