PA Sport Robert Rock overcame gusty conditions at the Pearl Valley Golf Estates on Thursday to lead the South African Airways Open after a solid opening round in Paarl as Greg Norman, the only Australian in the field found himself five strokes off the pace. Norman&aposs efforts, though, were hampered by heavy winds which made playing conditions extremely difficult, with only four players finishing under par. But it was Rock who led the way, shooting a two-under-par round of 70, to lead by one shot from a trio of South Africans, Ulrich van den Berg, Alex Haindl and Charl Schwartzel. The other big names all struggled with last year&aposs winner Ernie Els on five-over par and reigning US Open champion Angel Cabrera on eight over suffering the worst. Another home favourite Retief Goosen also had a tough round, but remains in contention at two-over par, while Norman is a further shot back after two bogeys and a double bogey in his final six holes. But it was world number 449 Rock who stood tall at the co-sanctioned European and Sunshine Tour event, shooting five birdies and two bogeys to edge ahead of the field. And he admitted afterwards that the wind failed to intimidate him in any way. “Starting off, even at 0700, it was blowing pretty hard. I had 29 putts and 10 fairways, so overall I was striking the ball well and holing crucial putts to save par and make birdies,” said Rock. “I didn&apost really make any lengthy putts. I made two putts over 10-feet and I drove well but had a lot of chances early that I just wasted.” “All my bogeys were not the fault of the wind, they were my own mistakes. I hit good shots and gave myself chances, but I also messed up quite a fair bit. Here if you hit a bad shot, you get punished.” Earlier on Thursday morning (South Africa time), the tournament lost one of its other big draws when two-time winner Trevor Immelman withdrew through injury. The 27-year-old completed just two holes before complaining of a rib problem that caused him trouble with breathing. It was later revealed that he had a lesion on the 11th right rib, which will be surgically removed next Tuesday, ruling him out for up to six weeks.