Leclerc was running a lonely third place in the Bahrain Grand Prix behind the dominant Red Bull duo, as Max Verstappen went on to lead a 1-2 in the opener until his Ferrari engine lost power and forced him out of the race on lap 40.
Speaking immediately after the race, Leclerc didn't know the cause of his retirement from the race but was already frustrated by Ferrari's pace deficit to Red Bull which he estimated to be one second per lap.
"I cannot say it feels good," Leclerc, who had his Ferrari's energy store in the power unit changed before the race, said.
"Obviously, there was quite a lot of work on that [over the winter] but we need to keep working because obviously first race and first reliability problem were not good.
"I was as confident as I could be, being one second off of the pace, which is not really confident, to be honest.
"Red Bull seems to have found something really big in their race pace.
"In terms of quali pace, they are actually pretty similar to us, at least we managed to extract the lap time yesterday, but then we come to the race and we are one second a lap off the pace which was huge.
"So we need to look into that plus the reliability."
Leclerc felt he could have held on to third place without the engine issue, the place going to Fernando Alonso, who beat Carlos Sainz and both Mercedes drivers to the final spot on the podium.
Leclerc did acknowledge the new threat from Aston Martin is present.
"They seem to be quick," Leclerc said about Aston Martin. "I think today third place was possible, I had a bit of margin with the guys behind and I was managing well in that last stint.
"But they were starting also a bit further back, so I don't know. Bahrain is also a very specific track so I hope that the picture can change a little bit for the next race, but we cannot rely on that as we need to work and find something."
