The GolfRSA National Squad player qualified for the 312-strong starting field of the prestigious championship alongside Ian Snyman from Western Province and Ross Sinclair from Gauteng North, who are both on golf scholarships at colleges in the United States.
McClatchie opened with an even-par 70 at the Riviera Country Club to tie for 28th and finished in the top 30 after an one-over-par 71 at Bel Air Country Club.
The Ekurhuleni golfer negated a double bogey at the par five eighth and further drops at the second, 11th and 16th with birdies at the first, fourth, seventh and the closing hole to finish joint 29th on one over 141.
McClatchie will face Walker Lee from Houston, Texas in the Round of 64 on the Riviera course. The American posted rounds of 72 and 70 to tie for 35th on two over 142.
“I had a tough day in round two,” said the reigning English Men’s Amateur Stroke Play champion.
“It was going really smoothly until the double at the eighth, which set me back a bit. Knowing the back nine was so tough, I knew it was a bad mistake, but I grinded it out. A few encouraging words from my dad on the bag that really kept me calm.
“I dropped two more shots on the back, but I finished with a birdie, which was really nice to gain some confidence and momentum going into the match play.
“I hit the ball the best I have probably ever, but I've just been struggling to score. A few too many mistakes, but for the match play that's not such a bad thing I'm really excited to get going and to test myself against these guys out here on an unbelievable golf course.”
Compatriot Ian Snyman missed top 64 with rounds of 71 and 75 and fellow South African qualifier Ross Sinclair also received his marching orders after rounds of 73 and 82.
Hayden Wood from the United States took the top spot.
The 21-year-old Wood made just two bogeys over 36 holes on his way to setting the championship stroke-play scoring record at nine under 131. Wood fired a 64 at the Riviera Country Club and returned a 67 at Bel Air to win by three shots from fellow American and local favourite Norman Xiong.
A 13-man play-off will determine the final eight berths for the match play on Wednesday, with the Round of 32 and the Round of 16 on Thursday. The quarter-finals and semi-finals are scheduled for Friday and Saturday, respectively, and the championship concludes with a 36-hole final on Sunday.