Toro Rosso driver Sebastien Buemi says his team's continued problems with the tires were the reason for his struggle in qualifying in Turkey.
"We had a very tough time, especially with the soft compounds, as we were never able to get the most out of them," said Buemi after finishing down in 18th position. "So the best thing we can do now is think hard about the race and ensure we have the best possible strategy.
"It will be a difficult afternoon, starting so far back and managing the tires, specifically the inevitable degradation on the front right. OK, starting 18th I'm not really thinking of a points finish, but we will still give it our best shot."
The problem also affected teammate Sebastien Bourdais, who was unable to escape the final row of the grid after lacking grip with the softer tires.
"All I know is that we lack grip and we are off the pace, even being two tenths off Seb," said Bourdais. "My first run wasn't too bad, but I had degradation on my next one.
"Then we changed the tire pressures a bit, but it seemed that as the session developed the option began to work better and I was running the prime which we felt suited us better.
"We've gone backwards a bit this weekend which is hard to take. In the race, I don't think the difference between the tires will be that much and in any case, it's not just the tires that are our problem this weekend."