Kyle Verreynne batted in the Lord's Test shortly after his grandfather fell seriously ill in the stands.
ESPNcricinfo has learnt that Verreynne's grandfather was struggling to breathe in the Edrich Stand and was stretchered out of the ground before being admitted to an ICU ward. He remains in hospital.
Verreynne was listed on South Africa's team sheet at No. 6 but was held back when his grandfather began having trouble and was helped by medical staff at the ground.
That was shortly before Sarel Erwee was dismissed. When Erwee was bounced out by Ben Stokes, South Africa's team management opted to send Marco Jansen in instead and inform Verreynne of the situation and he batted next.
Verreynne provided Stuart Broad's 100th wicket at Lord's when he edged behind to Ben Foakes for 11 after spending just over half an hour at the crease. South Africa went on to win the match by an innings and 12 runs.
Verreyne will remain with the South Africa squad ahead of the second Test, beginning in Manchester on Thursday.