Ireland claimed their first Test series victory in Argentina after overcoming some first-half jitters to seal a 23-17 victory over the Pumas in Tucuman.
Jonny Sexton slotted over three penalties and a conversion for the Six Nations champions, with Madigan adding two points following his try.
Ireland took the lead in the fifth minute when Argentina’s number eight Antonio Ahualli de Chazal was penalised, Sexton seized the three points with ease.
A minute later the tourists looked like they were on the scoreboard again when Sexton's cross-field kick picked out Zebo in space on the left wing, only for the Munsterman to run out of space and a toe in touch denied him a third international try.
Ireland had a one man advantage in the ninth minute when Argentina hooker Matias Cortese was sin-binned for an illegal chop tackle on Dave Kilcoyne, and once again Sexton had an easy job to convert the penalty to give Ireland a 0-6 advantage.
However Argentina coped easily with Ireland's numerical advantage and two minutes before Cortese's return, the numbers were evened up when Andrew Trimble was also sin-binned when he tackled Argentina winger Manuel Montero off the ball.
Nicolas Sanchez slotted the resultant penalty to halve Ireland's lead. Joe Schmidt's side looked certain to score the game's opening try, and only a forward pass from Jamie Heaslip stopped Chris Henry's drive to the try line in the 21st minute.
From the resultant defensive scrum, Argentina scored a try of their own. Captain Martin Landajo broke easily through the Irish defensive line, and although Zebo's covering tackle denied Amorosino a certain score, quick ball was presented to Landajo and his skip pass sent Joaquin Tuculet in for a simple try.
That try gave the home side a four-point lead, but eight minutes before the break Sexton landed a third penalty when Lucas Noguera Paz flew off his feet after strong carries from Kilcoyne and Heaslip. Despite that effort though, Ireland still trailed 10-9 at the break as Argentina looked to level up the series.
Sexton missed a slightly awkward penalty three minutes after the restart but Ireland recaptured the lead in the 51st minute when Eoin Reddan broke smartly off a rolling maul and sent Zebo in for a try. Sexton's conversion made it 16-10 to Ireland but the Racing Metro fly-half left the action following a clash of heads 15 minutes from time, with his former Leinster team-mate Madigan taking over the kicking duties.
He missed the target with his first effort but made amends when he converted his own try, which he made with a neat sidestep to score under the posts seven minutes from time to give Ireland a 23 points to ten victory.