David Kriel kicked a last-gasp penalty as the 14-man Bulls ended Leinster’s 12-game unbeaten run in the United Rugby Championship with a 21-20 victory.
The South African side had battled into the lead in Pretoria before wing Sebastian de Klerk was sent off for a reckless tackle on Andrew Osborne with five minutes to play.
Ross Byrne then kicked Leinster into a two-point lead, but the URC leaders gave away a scrum penalty with the clock in the red to hand Kriel the chance to land the winning points.
Despite the defeat, Leinster still hold a nine-point lead a the top of the table, while victory moved the Bulls up to third.
The Bulls took the lead when Keagan Johannes landed a penalty, but Leinster would respond with the first try moments later.
Tommy O’Brien kicked the ball into the Bulls’ 22 and Leinster recycled the ball quickly to allow New Zealand centre Jordie Barrett all the time and space required to race over the line.
Byrne added the conversion, but the Bulls’ task got even harder when prop Alulutho Tshakweni was sent to the sin-bin for a tackle.
Both sides exchanged penalties through Byrne and Johannes, but Leinster held a 10-6 lead at the break.
The URC leaders struck again three minutes after the restart when Andrew Osborne finished off a flowing move in the corner.
Osborne looked as if he had dropped the ball forward as he looked to touch down with one hand, but the TMO stuck with the on-field decision of try and Byrne again added the extras.
The Bulls had a gilt-edged chance to score their first try when Johan Grobbelaar made good ground, but Jan-Hendrik Wessels spilled the ball with the tryline gaping.
The South Africans got a deserved score when a rolling maul was brought down and the penalty try was awarded, and Thomas Clarkson was sent to the sin-bin.
Another maul gave the Bulls the lead with 10 minutes to play as replacement prop Grobbelaar crossed, but Kriel hit the post with his conversion.
However, there was a twist to come when De Klerk was sent off with five minutes to play for a reckless tackle on Osborne in the air.
Leinster pushed forward and won a penalty just inside the Bulls half, and Byrne’s superb kick from range went in off the post.
That looked like it would be the winning kick until the Leinster scrum collapsed with the clock in the red, and Kriel’s penalty split the posts to land a famous win for the Bulls.
Bulls: W le Roux; S de Klerk; D Kriel, H Vorster; S Jacobs; K Johannes, E Papier; A Tashkweni, A van der Merwe, W Louw; R Vermaak, JF van Heerden; M Cotzee, J Kirsten, C Hanekom.
Replacements: J Grobbelaar, JH Wessels, MSmith, R Ludwig, M van Staden, N Carr, Z Burger, D Williams.
Leinster: J O’Brien; T O’Brien, Cooney, Barrett, A Osborne; Byrne, McGrath (capt); Boyle, McKee, Slimani; Mangan, Snyman; Deegan, Connors, Culhane
Replacements: Smyth, I Soroka, Clarkson, Deeny, A Soroka, Penny, Gunne, Frawley
