Sebastian Vettel conceded he was "really disappointed" by Ferrari's pace during qualifying for the Monaco Grand Prix as he finished the session in fourth place.
Vettel and Ferrari languished down the order during Thursday's second practice session but moved to the front on Saturday morning, indicating that Ferrari was in the mix for pole position.
However, Vettel was able to record only the fourth best time in Q3, almost a second down on Red Bull's Daniel Ricciardo.
"Of course I'm really disappointed, because what we did on the car from Thursday to today was really good and we had improved it a lot," he explained.
"This morning we had a very good start, I knew that there will be a lot more to come and I wasn't worried at all, but as the qualifying progressed it was just getting more difficult for us to extract the grip.
"When you don't have the grip here it's more penalising than on another track, the car was starting to slide a lot and at this stage we don't understand why.
"While all the grid was going faster and faster, in the end we did the same fast laps we did at the beginning."
Team-mate Kimi Raikkonen was sixth quickest but will drop to 11th on the grid due to a gearbox penalty.
"For sure we did the right things, but we struggled to make the tyres work as we wanted," he said.
"They were too much on the edge of the grip, the rear was slipping or the front was sliding and in a track like this when you don't have a consistent good grip you lose a lot of time because of that."