The Leinster star injured himself in Saturday's Pro12 Final defeat to Connacht
Ireland will go to South Africa, looking for their first ever Test victory in the country, without their most influential player.
It is being reported in the Irish Independent on Thursday morning that Leinster star Johnny Sexton is to miss the three-test series due to a shoulder injury. The 30-year-old injured his shoulder on Saturday in Leinster's ten-point defeat to Connacht in the Pro12 Final.
Sexton played the full 80-minutes, but received treatment in the first half after being on the opposite ends of two heavy tackles in quick succession.
Ulster's Paddy Jackson looks set to step into Sexton's boots as first choice fly-falf with the Bordeaux-bound Ian Madigan the most logical choice to come into the squad as a replacement.
Sexton's injury is the second to have fallen upon a Leinster player since the 32-man squad was named. Luke Fitzgerald is also set to miss the tour with a knee injury.
The loss of Sexton will come as a massive blow to head coach Joe Schmidt. The tour is Ireland's first in South Africa since 2004. On that tour Ireland lost both of their matches against the Springboks.
Jamie Heaslip and Rob Kearney are the only Irish players in the squad to have played test matches in South Africa. Both men were part of the Lions team that played there in three tests in 2009. Richardt Strauss and CJ Stander will also know the conditions well. Both men grew up in the country.