The Italian, who left Force India to compete for the world champions for the last five races of the season, will fulfill a life-long dream when he clambers into the famous red car at his home Grand Prix this weekend.
Brazil's Massa, whose previous replacement Luca Badoer was dropped after two poor races, is not scheduled to race again until next year after suffering a fractured skull at July's Hungarian Grand Prix.
"I spoke to Massa on the phone, he said he was happy for me and that it had been the right decision to choose me," Fisichella told a news conference at Ferrari's Maranello base.
"I said I was really sorry for what happened to him and to recover quickly. 'When you want the car back, come and take it because this is your car. I hope to achieve what you would have,' I said."
Fisichella, who will also be Ferrari's reserve driver next season, added: "At 36 I'd lost hope. But obviously you never say never."
Schumacher to test 2007 Ferrari again
Force India's Fisichella gets drive with Ferrari
Badoer ready for Ferrari challenge
Schumacher warms up for F1 return in karts
When a spring fractured Massa's skull...