Crugnola was 1.7sec ahead of Roberto Daprà after five stages but lost control of his Lancia Ypsilon Rally2 HF Integrale on a right-hand turn 13.6 kilometres into the 27.85-kilometre Piana di Rascino test and slid down a ditch.
The two-time Rally di Roma Capitale winner and co-driver Luca Beltrame were unharmed but with their car stuck, their hopes of ERC glory are over.
Daprà now leads by 17.7sec over fellow Pirelli-equipped Škoda Fabia RS Rally2 drivers Teemu Suninen and Boštjan Avbelj.
Saturday’s deciding stage is due to begin at 18:45 local time.