American Paul Peterson defied torrential rain to fire a first-round 62 in the Joburg Open Thursday before the weather forced play to be suspended for the day.
The 28-year-old held a three-stroke clubhouse lead over Anton Rai and Paul Waring of England, Romain Langasque of France and Jbe Kruger of South Africa.
Seeking a second European Tour success after winning the Czech Masters last year, Peterson birdied nine holes and did not drop a shot.
"Birdieing half the holes is never bad so I felt really good out there," said the golfer from Tucson in Arizona.
"I got into a nice rhythm today, found the fairways with most of my drives and putted well."
Only one of three major winners in the 210-man field managed to finish with former US PGA champion Y.E. Yang of South Korea carding a 71.
Former British Open winner Darren Clarke of Northern Ireland and ex-Masters title-holder Trevor Immelman of South Africa were both two over after 14 holes.
Defending Joburg Open champion Haydn Porteous of South Africa was four under after 14 holes.
The par-72 east and par-71 west courses at Royal Johannesburg and Kensington Golf Club are being used for the tournament.
Competitors play one round on each course and the final two rounds on the more challenging east layout.