JOHANNESBURG, Dec 8, 2012 (AFP) - South African Tim Clark and Morten Orum Madsen from Denmark were tied in the lead by the end of the day, having carded five-under-par 60s at the Royal Durban Golf Club, reduced from the initial par 70 to par-65 over 5,594 metres.
The rain-hit tournament was also reduced to 36 holes.
Just as the round was finishing, the presidency announced the country's first black president, now 94, had been hospitalised for "medical attention ... consistent with his age."
"There is no cause for alarm," said presidential spokesman Mac Maharaj in a statement.
The inaugural one-million-euro tournament, named after the Noble Peace Laureate, was delayed two days after summer showers soaked the course this week.
Organisers have reduced the championship to a two-round competition, to finish by Sunday.
Clark, 36, shot six birdies and one bogey for his early lead before Madsen later caught up.
"It's really a case of when we did get to play, come out, try and play well and put yourself in a position," said Clark.
"So I'm happy to have done that; we obviously can't tell what the future holds, but I do hope we get to play some more golf."
With the fewer rounds comes pressure to perform more quickly than usual, said the two-time SA Open champion.
"Just come out and try to make birdies," said the 2010 The Players champion. "Normally you can sort of pace yourself, but right now you've got to go as low as you can and be aggressive
Rookie Madsen, fresh from qualifying school, started well but dropped a stroke on the par-five first hole.
His bunker shot was braked by South African Ruan de Smidt's ball on the second hole, and his par there got him going again.
"That was a nice momentum thing for me and I really got me going again. I played some really solid golf from there," the 24-year-old said afterwards.
Only one stroke behind, South Africa's Lindani Mdwandwe and Englishman Chris Lloyd are breathing down the leaders' necks.
Mandela spent almost three decades in prison for his fight against the apartheid government. He became South Africa's first black president at the fall of the white regime in 1994 and is revered as an icon of peace and reconciliation around the world.
Proceeds from the golf tournament will go to his children's fund, dedicated to bettering the lives of underprivileged youngsters.
South Africa hosts six European Tour events in the 2013 season.
Scores after the first round of the Nelson Mandela Championship at the Royal Durban Golf Club, reduced to a par-65 of 5,594 metres after rain delayed play for two days.
60 - Tim Clark (RSA), Morten Orum Madsen (DEN)
61 - Lindani Ndwandwe (RSA), Chris Lloyd (ENG)
62 - Colin Nel (RSA), Matthew Southgate (ENG), Christiaan Basson (RSA), Maximilian Kieffer (GER), David Horsey (ENG), Shaun Norris (RSA), Julien Quesne (FRA), Desvonde Botes (RSA), Sam Little (ENG), Eduardo de la Riva (ESP)
63 - Richard Bland (ENG), Carlos Del Moral (ESP), Allan Versfeld (RSA), Mikael Lundberg (SWE), Bjorn Akesson (SWE), James Kingston (RSA), Pablo Larrazabal (ESP), Jaco Ahlers (RSA), Steve Webster (ENG), Matthew Nixon (ENG), Robert Coles (ENG), Marc Warren (SCO), Bradford Vaughan (RSA), Oscar Floren (SWE), Alessandro Tadini (ITA), Andrew Marshall (ENG)
64 - Espen Kofstad (NOR), Emiliano Grillo (ARG), Dominic Foos (GER), Mark Williams (RSA), Seve Benson (ENG), John Parry (ENG), Soren Kjeldsen (DEN), Tyrone van Aswegen (RSA), David Hewan (RSA), Michael Jonzon (SWE), Rhys Davies (WAL), Richard Finch (ENG), Doug McGuigan (RSA), Estanislao Goya (ARG), Adilson Da Silva (BRA), Michiel Bothma (RSA)