Seven-times drivers world champion Michael Schumacher admitted he was bewildered by his own lack of pace after qualifying only eighth on Saturday for Sunday's Turkish Grand Prix.
The 42-year-old German had shown good speed for Mercedes during the morning final practice session, but was unable to do it again in the critical hour in the afternoon when team-mate and compatriot Nico Rosberg was third fastest.
Defending champion and current championship leader Sebastian Vettel took pole position as Red Bull swept the front row with Australian Mark Vettel was second behind him.
"I'm not happy at all, being so far off, that's a bit unusual," said Schumacher.
"It didn't really work out at all. The grip for whatever reason wasn't there compared to what I had this morning. I struggled already in Q2.
"The track certainly was better than it was this morning, but we couldn't reproduce what we did this morning. So, we need to understand what's going on.
"The more I pushed, the more things went wrong - and in the end there was no grip left."
Rosberg - son of Finland's former world champion Keke - by contrast was highly satisfied.
"I am happy for sure. It is really nice to see the progress we are making. When you see where we were four races ago, we are learning from mistakes we made and making most of car we have."
"That is really good and the team have been doing a good job there, but we are still not where we wanted to be, so every race we continue to keep on pushing."
Rosberg said he is also confident he will overtake Red Bull's Australian Mark Webber, starting from second, right at the start.
"I am going to have a stunning start. I am on the clean side of the grid so I will go straight past Mark and then we will see," he said.