Du Plessis, 36, was dismissed meekly for 199 caught by Dimuth Karunaratne at mid-on off the impressive Wanindu Hasaranga’s bowling, falling short of the rare feat as South Africa posted 621 in reply to Sri Lanka’s first innings score of 396.
The former South Africa captain’s dismissal ushered in the end of the Proteas’ batting innings, falling at 7-609, with the final four wickets being taken for only 12 runs.
Du Plessis had combined for a 133-run seventh-wicket partnership with Keshav Marahaj (73), while earlier in the innings Dean Elgar (95), Temba Bavuma (71) and Aiden Markram (68) made meaningful contributions without reaching triple figures.
Hasaranga was the best of the bowlers, taking 4-171, but Sri Lanka have been hit hard by injury, losing Lahiru Kumara, joining Kasun Rajitha and Dhananjaya de Silva on the sidelines.
To make matters worse, the tourists lost two wickets before stumps to finish 2-65, trailing 160 runs with eight wickets in hand.
Kusal Perera (33no) and Dinesh Chandimal (21no) will resume on day four, with Karunaratne (6) and Kusal Mendis (0) both dismissed by Lungi Ngidi.
Du Plessis’ career best knock has put the Proteas in a strong position to claim the win in the run feast at Centurion but finding eight wickets on day four will be key. Ngidi’s early inroads certainly will be a mental boost.
Sri Lanka’s injury woes will be a major issue for the tourists, with de Silva injured while batting and ruled out for two weeks.
“The way it (the injuries) went today, I’ve never seen that,” Sri Lanka batting coach Grant Flower said.