Sam Prendergast led a young Leinster side to a dramatic comeback victory over the Lions, as the Ireland U20s fly-half slotted a match-winning penalty at the death.

Leo Cullen’s men came from 15 points adrift to stretch their unbeaten run to 23 games this season and secure their first victory in South Africa.

The 20-year old from Newbridge looked perfectly at home at one of the most iconic stadiums in the world as a Leinster side, some fourth or fifth in the pecking order, survived having two men in the bin and still came good at the end at Ellis Park.

Prendergast led the way throughout as Leinster, inevitably, went through some poor phases given the make-up of the side, but they never lost sight of the finishing line even when they trailed 26-21 going into the final quarter.

Lions, with only an outside chance of making the qualifiers, had the bonus point in the bag by the interval when they turned around leading 26-14 after a free-flowing opening half where both defences were suspect.

Most of the fringe Leinster players getting a run in South Africa know they have to make an impact given the scarcity of game time, and Georgian prop Vakhtang Abdaladze wasted little time on his first start, taking an excellent pass from Prendergast to run a try in from outside the 22.

Lions hit back with a try from winger Edwill van der Merwe after 14 minutes and as the game opened up they punished sloppy Leinster defending with Gianni Lombard’s grubber catching out Dave Kearney as he retreated and it fell kindly for the Lions out-half to collect his own kick and score.

Max Deegan was unable to ground the ball after a brilliant bust off the base of a scrum but the reprieve was short-lived for the hosts as Liam Turner cut a super line through the centre to and edge them 14-12 in front.

Poor defending was punished before the break as Marius Louw and Francke Horn got in for tries to lead 26-14 at the interval, but Michael Milne became the second Leinster prop to score when he crossed nine minutes after the restart off a good lineout move for his seventh try for the province.

Leinster lost scrum-half Nick McCarthy and full-back Chris Cosgrove to yellow cards in a two minute spell for deliberate knock-ons and this helped Lions push the gap out to 36-21 with a penalty try.

A long range penalty from Prendergast after 63 minutes, which also helped run down the clock, was the catalyst for Leinster’s remarkable comeback.

Rob Russell came on and continued his astonishing scoring run, becoming Leinster’s top try scorer this season with his tenth when he scored in the right corner.

Prendergast missed his only kick of the afternoon, but they pushed on and Cosgrove cut through and did superbly to score in the tackle, with the conversion tying the match five minutes from time.

And it was Leinster who pushed on from there, a 14-phase move inside the home 22 ended with a penalty which Prendergast slotted to claim an astonishing victory.