Hashim Amla (125*) and JP Duminy (155) put on a 292 run partnership for the third wicket as South Africa piled on 338 runs to end day one in a commanding position.
Having won the toss, du Plessis decided against unleashing his four headed pace attack, deciding to bat and set the tempo with a big score.
The hosts made two changes with Wayne Parnell getting a rare go in place of Kolpak deal holder Kyle Abbott while Duanne Olivier was handed a debut, in place of the spinner Keshav Maharaj.
Sri Lanka went in unchanged with one eye on a consolation win and hopes with not getting white washed in the Rainbow nation.
Having been sent in to bowl, Mathews came out licking his lips with a juicy track at his disposal. The South African opening pair had other ideas as Dean Elgar and Stephan Cook saw off the new ball with relative ease.
Photos: Sri Lanka v South Africa 3rd Test – Day 1
Photos of the Sri Lanka v South Africa 3rd Test – Day 1
Angelo Mathews made the vital breakthrough three balls following the water break as he trapped Cook plumb in front for a hard earned 10 off 41 balls. Five balls later, Dean Elgar fell victim as he was caught out by Karunaratne off the bowling of youngster Lahiru Kumara.
With two quick wicket on 45, Sri Lanka smelt blood and continued the rampage on attack. Amla was joined by Duminy as the two experienced batsmen shrugged off the visitors attack holding strong through to lunch.
In the final over before lunch, Dhananjaya De Silva grassed an easy opportunity off the bowling of Suranga Lakmal as Amla edged to gully with just 5 runs to his name.
Amla made the visitors pay for the missed chance as he along with JP Duminy went on to put on a 292 partnership for the third wicket.
The Lankan bowling did not have the sting in the tail as the pair batted through the whole of the second session piling pressure on Mathews and his lads. The visiting captain tried hard to get a crucial breakthrough but failed with all tactics as Amla and Duminy carried on their merry way. The duo put on 114 runs in the second session continuing to put the visitors under the pump.
The third session was more of the same for the hosts as Amla and Duminy continued to add runs at a good rate. The highlight of the third session was Hashim Amla becoming the 8th batsman to score a century on his 100th test match.
With the new ball available in the 80th over, Angelo took matters into his own hands taking the new ball but miserably failed to make a breakthrough.
Lahiru Kumara was the man to do it again for Sri Lanka as the promising youngster managed to nick-off Duminy for 155 in the 89th over as the hosts cruised to a mammoth 338 to end day one.
