Dean Elgar scored a half century to go with his first innings century as South Africa profited from dropped catches to reach 157 for three at tea on the fourth day of the first test against New Zealand at University Oval in Dunedin on Saturday.

Elgar, who scored a patient 140 in South Africa's first innings of 308, was on 73, while captain Faf du Plessis was on 16 with the Proteas lead now 124 runs after New Zealand had been bowled out for 341 on Friday.

With rain forecast for virtually all of the final day on Sunday, New Zealand needed to make the most of their opportunities but only have themselves to blame for not being in a better position having dropped Elgar twice and JP Duminy once.

Duminy was dropped at first slip by Tom Latham when he was on six, while Elgar was spilled on 35 by wicketkeeper BJ Watling just before the lunch break.

The opener was then dropped after lunch on 48 by substitute fielder Colin de Grandhomme, with the added frustration of the ball almost travelling to the boundary for the left hander to score two runs and bring up his sixth test half century.

He was given out caught behind by Watling on the final delivery before tea but had the decision overturned on review.

The hosts also had two lbw appeals on Duminy turned down, with one that would have been overturned had they asked for a review.

Duminy was eventually given out lbw in the middle session, when he was trapped in front by Neil Wagner for 39.

Hashim Amla was the only wicket to fall in a disrupted first session, when he spooned a catch to substitute fielder Tim Southee off Wagner to be dismissed for 24.

Play had been due to begin 10 minutes earlier than the scheduled start of 1100 (2200 GMT) after a fire alarm in the main stand forced the evacuation of the entire venue and held up play for about 30 minutes on Friday.

Light rain, however, delayed the start for about 40 minutes with South Africa resuming on 38 for one.