Van Zyl lies in 27th place, eight shots off the pace set by Aussie Marcus Fraser who scorched his way around the Olympic golf course in 63 blows.
The 37-year-old got his round off to a poor start as he fell to two-over after four holes. A birdie at the par three-eighth before the turn, steadied the ship as he moved through nine holes in one-over.
A much more consistent homeward nine followed, sprinkled with a solitary gain at the par three 14th. A string of pars down the stretch meant Van Zyl signed for an even par opener, but with 26 players ahead on the leaderboard he will have much work left to do to get into medal contention.
Some way behind Van Zyl is compatriot Brandon Stone who settled for an opening four-over 75. The 23-year-old occupies 56th place in the field of 60.
Despite coming out the gates in red hot fashion with two birdies in a row to start, Stone dropped three shots before the turn to fall to one-over. Two more bogies and a double followed, offset by a lone birdie at the par-three 17th as he signed for a back nine 39.
Non-playing team captain Gary Player, 80, will have to find some way to inspire his young charges if the Rainbow Nation hope to be in contention on the weekend.
– African News Agency (ANA)