Rossi was thrown from his Movistar Yamaha bike and skidded across the gravel as he put in some last-minute preparation for qualifying on Saturday.
The Italian was able to take part in qualifying and will start from seventh on the grid in the race in Brno.
Former world champion Rossi is now praying that he suffers no ill-effects following his crash as he attempts to make it back-to-back podium finishes.
Reliving his accident, Rossi said: "I was pushing a lot and my pace was fast, then I entered turn 11 a bit wide and lost the front.
"I damaged the small finger a little.
"It's important to have no fracture so it looks good.
"Hopefully there are no problems for the race."
Championship leader Marc Marquez is on pole for Sunday's as he goes in search of a record 11th straight win at the start of a season.