By then Ulster's Jared Payne had already crossed for their first try and his clubmate Paddy Jackson - in the absence of the injured Jonathan Sexton - kept the scoreboard ticking over with his right boot.
Lwazi Mvovo replied for the Boks - in their first game under new head coach Allister Coetzee - but after the break Munster scrum-half Conor Murray went over and Jackson continued his fine form from the end of the Guinness PRO12 season to remain unflappable from the tee.
And despite Pieter-Steph du Toit's late interception, the 14 men of Ireland held firm for a magnificent 26-20 victory that will live long in the memory.
Wales were also in action on Saturday against New Zealand and while they did not walk off with victory they will take much encouragement from their 38-21defeat.
They led 21-18 with an hour to play after tries from the impressive Taulupe Faletau and Osprey Rhys Webb in the first half.
But the world champions turned the screw late on and skipper Kieran Read was one of the players to cross late on they sealed victory in the first of the three Tests.
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