Champions Red Bull are on a run of 15 successive wins dating back to last year but that too looked set to end in Sunday's hot and humid night race with Verstappen due to line up 11th on the starting grid and teammate Sergio Perez only 13th.
Asked if victory was now off the table, the Dutchman, who has yet to finish lower than second this season and won 12 of 14 races, told reporters: "Yeah, you can forget about that.
"You can't pass. On other tracks, you can start last and win the race. But not here."
The team that have won every race this season suddenly lacked balance and power with their two drivers too slow to make the cut for the final top 10 shoot-out at the Marina Bay Street Circuit.
"That was... shocking, absolutely shocking experience," Verstappen said over the team radio after being pushed down the order and out of contention by AlphaTauri's rookie stand-in Liam Lawson.
"I don't want to sound too dramatic, but it was a very tough weekend (and) in qualifying...it's definitely been a long, long time (since) it's been like this," he told reporters.
"The first big problem that I had was that I couldn't brake late and hard... and, you know, on a street circuit that is something very crucial."
Team boss Christian Horner said changes made after Friday's practice had not worked.
"It's very, very confusing to have dropped the amount of pace we have," he told Sky Sports F1 television.
"The car is not responding to changes - understeer, oversteer, braking issues... a lot for us to understand tonight and it will be very, very tough for us to make good progress tomorrow, but we will be trying very hard."
The city-state's street circuit has been shortened from last year, with two fewer corners due to construction works, adding another new factor.
Still, with a 145-point lead over nearest rival Perez atop the championship table and every chance of that expanding further on Sunday, Verstappen was fatalistic about the streak running out of road.
"I want to win, but when it's not possible you have to accept that," he said.
"We had a really good run anyway...I would always take a season where we're winning this much and having one really bad weekend, rather than the other way around.
"It's more important we understand what we did wrong."
