Max Verstappen said he was finding it "extremely difficult to be consistent with the car" despite winning the sprint race on Saturday and claiming pole position for Sunday's Miami Grand Prix.
Red Bull's reigning world champion and championship leader, who has won four out of five grands prix this season, secured his seventh straight pole position with another dominant drive.
Ferrari's Charles Leclerc, whose fastest lap was 0.141 seconds behind Verstappen, will start second with his teammate Carlos Sainz in third place and Verstappen's Red Bull partner Sergio Perez fourth.
Three-time world champion Verstappen has won both previous Miami Grand Prix races but never from pole and he said he still found qualifying tricky.
"Every single year that we come here, I find it extremely difficult to be very consistent with the car feeling, the tyre feeling over one lap," the Dutch driver said.
"It's not the single most enjoyable lap of my career just because of how slippery it is. You are not very confident on the lap but we are on pole and of course that is the most important thing."
Leclerc said it had been hard to manage the tyres, with overheating a problem, but said his performance in the sprint race gave him encouragement.
"That's where we lost a little bit of time, however the race is long tomorrow, we showed good pace this morning (in the sprint race) and I hope we can put Max under a bit more pressure," he said.
Sainz underscored just how tricky it had been for drivers to deliver their fastest lap on the course around Hard Rock Stadium, home of the NFL's Miami Dolphins.
"It's really tricky around here with a new soft. Every lap is a bit of adventure," he said. "With the wind you don't know what will happen. Keeping all that in mind, the laps were not too bad.
"You always finish the lap and think you could have gone so much faster, but it's almost impossible to put a perfect clean lap around here."
McLaren's Lando Norris will start in P5, just ahead of the Mercedes pair George Russell and Lewis Hamilton.
Earlier, Verstappen cruised to victory in the sprint race, finishing 3.3 seconds ahead of Leclerc. The Dutchman led from pole and was never challenged after a chaotic opening lap.
Verstappen's teammate Perez was third as the world champions gave themselves a points boost.
The Red Bull driver held off Leclerc's strong start to secure his place at the front but there was plenty of action and incident in the middle of the pack.
Haas's Kevin Magnussen and Mercedes' Hamilton jousted hard but in the end, the Dane picked up three penalties, adding 25 seconds to his time, after frequently leaving the track and gaining advantage.
Hamilton also received a penalty, leaving him outside the points positions in 16th after speeding in the pit lane.
The safety car was brought out after the first lap, which saw a startline incident involving Hamilton, Fernando Alonso, Lance Stroll and Norris.
But away from those skirmishes, it was business as usual for Verstappen, who added another eight points to his season tally with the victory.
"I think my engine wasn't good in the start and so then I had to speed it a bit, luckily everything worked out in turn one," said Verstappen. "Then we had the safety car just to calm things down a bit after that. Steadily we could increase the gap a little bit, but it wasn't entirely perfect so we still have a bit of work to do."
Australian Daniel Ricciardo, of RB, finished fourth in the sprint after holding off Ferrari's Carlos Sainz, but his joy was shortlived; he will start in last place on Sunday after a disappointing qualifying session.
Magnusson accepted his penalties were "well deserved" and Hamilton said he had enjoyed the duel.
"That's pretty honest of him and I think that's pretty cool," the British driver said. "We had a good race. It was a little bit on the edge in some places, but that's what I love. I love racing hard and, for me, I wasn't really frustrated or anything."
