Unfortunately, Hernández´s plans did not work out for him as he injured his back playing for the Natal Sharks. Despite being well below 100%, he continued playing Currie Cup rugby and put in some star performances including a 24 point performance vs the Bulls in Round 10. The extent of his injury would not become known until latter on but it was enough to rule him out of international duty for Argentina´s three match tour of England, Wales and Scotland in November 2009. In January 2010 it was confirmed that his injury required back surgery and Hernández was ruled out of playing Super Rugby as well as representing Argentina in the June test matches vs Scotland and France. He would return, however, for the 2010-2011 season with his new club - Paris´s Racing Metro.
In the following video the South African commentators incorrectly say Hernández´s try, which he scored at 1:35, was scored by Andries Strauss.