Jenson Button said he could offer no explanation for his qualifying struggles after only managing 17th on the grid for Sunday's Brazilian Grand Prix.
The McLaren driver had shown promising pace during Friday practice but was eliminated in the first part of qualifying, while teammate Fernando Alonso, whose FP2 running was compromised by ERS problems, claimed a Q3 spot in 10th. The Briton was left frustrated by his lack of competitiveness on Saturday.
"The car was well balanced yesterday and 10th quickest and today it's completely different cars," Button bemoaned. "Obviously you have a new engine, new gearbox, new rear end on the car but still when it's cooler you normally pick up a bit of rear grip.
"From the word go this morning I've been off the pace. Yesterday I was 10th quickest and today we are miles off the pace. It's frustrating because there's no major reason for it. Yesterday I was very confident with the car, especially the rear end. Today it's the opposite, so annoyingly different."
Button -- who sealed the championship in Brazil in 2009 -- won a chaotic 2012 Brazilian Grand Prix in mixed conditions and admits he needs some wet weather to come into play again on Sunday if he is to have any chance of salvaging a positive result.
"Maybe we could race in reverse or something. It's very annoying because I felt confident in the car yesterday and today nowhere. Tomorrow's another day, so only one more qualifying left, which at the moment I'm quite happy about. The last six races have been terrible, I don't know why.
"I've only got one more qualifying session left and hopefully it's better than this one. We can't really go back from that position so hopefully its foreword. Hopefully it's mixed conditions to give us some opportunity at least."