The triple Formula 1 world champion, who has won five of the first seven races, saw his record-equalling run of eight pole positions in a row ended by Ferrari's local hero Charles Leclerc.
That was only part of the pain, however, with the Dutch driver identifying what he called a basic flaw in a car that started the season in dominant fashion but has looked increasingly vulnerable.
"The car is like a go-kart, it is like I am running without a suspension. It is jumping around a lot, and not absorbing the bumps or kerb strikes," he told reporters after a last flying lap in which he scraped the tyre wall.
"In the last corner, the amount of times I almost jumped into the wall was pretty incredible.
"We have had this problem since 2022, so it is not something new. For the past few years we have had a car advantage so it gets masked, but with everyone catching up when you don’t improve your weakest point, you get found out," he added.
"It is a fundamental problem so it will not get fixed in weeks."
Leclerc's pole lap of one minute 10.270 seconds was nearly three tenths faster than Verstappen's best.
It was the first time since Mexico last October that Verstappen, who won in Monaco in 2021 and 2023, had not secured at least a front row slot on the grid.
It was also his lowest starting position since the U.S. Grand Prix that same month, which he went on to win in a season of unprecedented dominance.
Monaco is a race where overtaking is extremely difficult and where the winner has come from lower than third place on the grid only 10 times since 1950.
"The race is pretty much done barring safety cars. But we will come back fighting," said Red Bull team boss Christian Horner.
Verstappen described Saturday's performance as 'worst case scenario' and said some other tracks this season could be just as bad.
"I am pushing flat-out. The car is super tricky. I drive into turn one, go over the bumps, and the car snaps on you. The car is on a knife's edge to drive," he said.
"Wherever there are bumps it was just jumping around a lot so I am just driving around that. I was surprised how close we were in qualifying but I guess some of the others did not nail the lap."
Team mate Sergio Perez, another former Monaco winner, qualified only 18th.
