Dale Steyn on Wednesday became South Africa's leading Test wicket-taker as Pakistan struggled on the opening day of the first Test at SuperSport Park, Centurion.
Pakistan were 76 for four at lunch after winning the toss and batting on a well-grassed pitch on a hot day.
Steyn and fellow fast bowlers Kagiso Rabada and Duanne Olivier all took wickets.
Azhar Ali, one of only three Pakistanis with previous Test experience in South Africa, was unbeaten on 31 at the interval.
Rabada struck first, trapping Imam-ul-Haq leg before wicket for nought with a full delivery in the second over. The batsman wasted a review of a decision from umpire Bruce Oxenford which never looked in doubt.
Steyn claimed his 422nd Test wicket, going past previous record-holder Shaun Pollock, when Fakhar Zaman edged him to third slip for 12, sparking exuberant celebrations from his team-mates.
Rabada lifted his new ball partner onto his shoulders as other players rushed in to congratulate him.
Shan Masood, playing in place of Haris Sohail, who suffered a knee injury during the pre-match warm-up, looked competent in scoring 19 before being bowled off his thigh pad by Olivier, who followed up by getting Asad Shafiq leg before for seven.
Shafiq reviewed Oxenford's decision but replays showed the ball would have hit the bails in the 'umpire's call' zone.