Sauber's Kamui Kobayashi and Sergio Perez said their cars were simply off the pace in Korean Grand Prix qualifying, as they struggled to 14th and 17th on the grid.
After appearing to take a step forward with a new update package in Japan, Sauber never looked like reaching Q3 at Yeongam.
"We have had a difficult time here so far," said Kobayashi. "Fourteenth on the grid is obviously not what we were hoping for, and we are quite far away from our competitors.
"The main problem is still a lack of grip, which is caused by a combination of factors. My lap as such in Q2 was OK. I can't complain about traffic and didn't make a mistake. It was pretty much the best I could achieve today."
Perez, who will start 17th, said he compounded his problems with a scruffy Q2 lap.
"For me this was a very bad qualifying," said the Mexican. "After our only dry running was this morning and also for me the track is new, I am not happy with the balance and the setup of the car.
"I didn't feel at all confident in the car. My final lap in Q2 was particularly bad because I hadn't got the brake balance right and had the fronts locking. I now have a bad grid position and I think we should go for an aggressive race strategy."