Romain Grosjean has billed his qualifying showing for the Mexican GP as the "worst" of his career after finishing P21.
The Haas driver was slowest of all as only 21 of the 22 drivers took to the track in Saturday's qualifying with Jolyon Palmer out with a cracked chassis.
Grosjean's best time, a 1:21.916, was over half a second slower than the time Manor's Pascal Wehrlein clocked to get into Q2.
"Starting last on the grid I think never happened to me before," the Frenchman told NBCSN.
"Probably the worst qualifying of my career. We just need to understand why it's happening because clearly something is not right.
"The car is nowhere. I don't know what's happening. It was good in FP1, it was alright in the first run this morning, and after that the car has just been nowhere.
"We need to try to analyse it, because something clearly is not right.
"It's enough doing miracles on Sunday. I think now we really need to understand what we are missing.
"Because last on the grid just really is not acceptable for us.