Adam Reynolds has lauded South Sydney's reserve grade players for preparing him for Saturday's tense final-minute field goals in their NRL semi-final win over St George Illawarra.

Reynolds became the first player to kick three field goals in a match in 21 years in the Rabbitohs' 13-12 defeat of the Dragons, booting all of them in the final 11 minutes of the match.

Coach Anthony Seibold revealed post-match his team had made a point of focusing on situational practice this season, before Reynolds kicked them into a preliminary final against arch-rivals Sydney Roosters next Saturday.

"We've trained for those sort of moments," Reynolds said.

"All our reserve grade boys, the boys that don't play week in week out, they do a fantastic job for us, putting us under pressure in those key moments.