Toro Rosso are confident of rebounding after a trying start to the team's Korean Grand Prix weekend.
Neither Daniel Ricciardo nor Jean-Eric Vergne had the pace to run inside the top as the duo struggled in Friday's two practice session.
Ricciardo eventually finished P16, 1.879s off the pace, while Vergne was one place higher and a tenth quicker.
"Unfortunately we were on the back foot right from the first session, because the pace wasn't there," said the Red Bull-bound Aussie.
"We really thought we could cure it for the second session, but that wasn't actually the case.
"However, I still believe this is a track that should suit us, but we are leaving it to the last minute to be competitive tomorrow.
"It would have been nice to have a good Friday session, so now we just have to work hard to turn things around."
Meanwhile, Laurent Mekies, the team's head of vehicle performance, conceded that it was an "unhappy" start for both drivers.
"An unusual two sessions for us, as we are unhappy with the balance of both cars and, as a result, our performance level was not what we were expecting on a track layout that should suit us quite well," he said.
"There is no reason why tomorrow, we cannot be back where we should be on this type of track. Clearly we have hit some performance limitations on both cars and now we must try and give Jean-Eric and Daniel a well balanced car for tomorrow."