The Napoli goalkeeper suffered a torn anterior cruciate ligament in his right knee during his side's 0-0 draw with Swansea in the Europa League
The 23-year-old was handed a start for the Europa League trip to Swansea but was forced off shortly before half-time with what was later diagnosed as a tear to the anterior cruciate ligament in his right knee.
Napoli have confirmed the Brazilian will undergo surgery in order to repair the damage, but while his season is over, Rafael has assured Partenopei supporters he will do his utmost to be ready to return as soon as possible.
"I'm confident I'll be back stronger than ever," he wrote on his official Instagram page. "I'm proud, and very happy to play here. I'll be back soon."
Rafael, who joined the club from Santos last summer, has made 11 appearances for Napoli in all competitions this season, with Pepe Reina the preferred choice for Rafa Benitez at the San Paolo.
Napoli face a Serie A meeting with Genoa on Monday in their next encounter.