The two-time U.S. Open champion, who also won the 2002 British Open, injured his left knee in a boating accident in July and underwent surgery.
'The knee is still uncomfortable, but the doctor assures me there's no way a golf swing will damage my knee,' Els said Wednesday. 'It tends to swell up at the end of each round and that's the worst part really.'
He returns to tournament play Thursday in the Nedbank Golf Challenge.
'It's been 4 1/2 months since I played in a tournament,' Els said. 'I'm feeling pretty anxious. I felt very unsure the first time I played 18 holes.'
Els did so at the end of October in Wentworth, England. This time, he'll face hot and humid conditions on the 7,832-yard, par-72 Gary Player Country Club course against several top players.
Els is the most experienced player in the 12-man field with 13 appearances and three victories. But he faces a tough group led by defending champion Retief Goosen, Sergio Garcia, Adam Scott and Luke Donald.
'It helps if you've been here before because then you're used to the crowds, the course, the grandstands and everything else,' Els said. 'I'm just fortunate to have my health back, to be playing again. The last 20 weeks or so have been a period of reflection for me.'
Also entered in the $4 million event are Jim Furyk, Darren Clarke, Angel Cabrera, Stewart Cink, Tim Clark, Kenny Perry and Chris DiMarco.
Clarke finished third in 1999 and fourth in 2003, but has won at Sun City -- in the Dimension Data Pro-Am.
Furyk has posted low rounds here. He shot a 64 in 1998 and a 66 last year -- the lowest round of the week.