Having looked good in Friday's practice, Leclerc was less happy in Saturday's FP3 session, and in qualifying he struggled with his front tyres.
He was fourth in Q1 and second in Q2, but tried a front wing change for his final run in Q3 in an attempt to find more performance.
Leclerc was left a frustrated fifth after the "very aggressive" wing adjustment failed to pay off.
"To be honest, I think it's starting from much earlier in the weekend," he said when asked by Motorsport.com about his Q3 struggles.
"In FP3 already, I felt like it was going away a little bit from me, but I was confident that it will come back the feeling in qualifying, as is normally the case.
"Whenever we have a strange feeling in FP3, then you put the new tyres in quali, low fuel, and everything comes alive again.
"Today wasn't the case. I struggled quite a lot with the front tyres, until the last run in Q3 where I went very aggressive with the front wing to try something, and I went the other way.
"But all-in-all, it hasn't been a clean day for me, I haven't been driving as well as yesterday. But tomorrow the race is long, and I'll try to maximise everything."
Leclerc admitted that FP3 had also opened up his eyes to Red Bull's performance after Verstappen grabbed pole by nearly three tenths.
"I saw that Red Bull started to put the engine on full power," he said. "And from Turn 7 to Turn 9 I think we were losing already three tenths this morning. So that was huge.
"And then from that moment onwards, I felt like the pole position would have been difficult. But then in Q1 we were very strong, so I was, 'Okay, maybe.' At the end, it wasn't.
"I think realistically, it's going to be difficult to target the win because Max [Verstappen] is going to be too strong. Checo [Perez] might be a target.
"But they seem strong once again because they have more margin than what we initially thought they had yesterday.
"But all-in-all my target is obviously to try and come back and be on the podium. And if that's beating Checo, then we'll try and do that."
The hard tyre remains an unknown as teams have saved it for the race.
Asked if it could favour Ferrari, Leclerc added: "I hope so. But again, we'll focus on ourselves, and if we can put them a bit more pressure, which hasn't been the case until now, then I'm happy to do so."
Leclerc cited his own tyre preparation as one reason for his struggles.
"The feeling wasn't right," he said. "From FP3 it was much more difficult to have a clean lap. Yesterday, every lap I was doing was all clean, all good.
"And today just there was either one axle or the other that will go away, which is mostly down to tyre preparation.
"And I don't think I've done a great job on that today. So that's a snowball effect then for the rest of the lap. So that's why I think I messed up."
