Belgium's Nicolas Colsaerts leads the Volvo Golf Champions by four strokes after surging clear of the field with a course-record 64 at Fancourt in South Africa.
Padraig Harrington was three behind until he finished with a double-bogey seven that left England's Tom Lewis and home hopes Thomas Aiken and Branden Grace in joint second.
Open champion Darren Clarke managed only a 74, but that was one better than Masters champion Charl Schwartzel in the winners-only 35-man event.
Even allowing for the small field, Colsaerts' lead after day one was impressive, and there have only ever been seven events in European Tour history where someone has been further in front after 18 holes.
"Exceptional, but so is he," said Colin Montgomerie of Colsaerts' nine-under-par round. "He is fantastic - potentially as good as it gets."
Despite such praise, Colsaerts has only ever tasted victory once in nearly 200 European Tour starts and that will encourage the 34 players left trailing in his wake.
However, Open champion Clarke already has 10 strokes to make up - he was wearing contact lenses for the first time, but rustiness was his problem.
Until he reached the 549-yard 18th, Harrington was the one doing his best at trying to reel Colsaerts in, but a bad drive and three putts led to a double bogey and a 69.
"Such is life," said the Dubliner, 89th in the world and trying to get back into the top 64 in time for next month's Accenture World Match Play in Arizona. "It was a very comfortable six under for 17 holes, but it's a nasty tee shot and that was a mental error."
Instead, England's Lewis and South Africans Aiken and Grace, who qualified by winning the Joburg Open on Sunday, share second spot.