Australian Ricciardo told reporters that he expected to have to take a hit for the penultimate race of the season after engine problems halted his Renault-powered car at the previous round in Mexico.
"I may have to take another penalty. It is likely," said Ricciardo.
"We could maybe avoid it but it is probably going to put us in a risk again of not finishing. We tried to avoid it last weekend and it still didn’t happen. I probably won’t have a big one (penalty), but if it is, it could be like 10 places."
Ricciardo's Dutch team mate Max Verstappen has won two of the last four races, including Mexico, while the Australian has suffered a sudden run of reliability problems.
French driver Gasly and his New Zealand team mate also spoke of the likelihood of penalties once Friday practice is out of the way.
"It looks like we will have to start from the back of the grid, which makes it of course pretty difficult. But it is something that we cannot really change," said Gasly.
Toro Rosso are fighting for sixth place in the constructors' championship and lead seventh-placed Renault by a mere five points.
The Italy-based team are switching from Renault power units to Honda next year.
(Reporting by Alan Baldwin, editing by Ed Osmond)
