Despite heading a Ferrari 1-2 in practice, admitting that it's too good to believe, Charles Leclerc prefers to remains realistic in terms of a Monaco upset.

Sidelined by a gearbox issue in FP1, in Thursday's second session Charles Leclerc and teammate Carlos Sainz finished first and second, edging out the Mercedes pair and Max Verstappen.

Yet while some were wondering whether the Maranello outfit, which has 9 wins in the Principality to its credit, might pull off a surprise this weekend, the Monegasque prefers to keep both feet firmly on the ground.

"I'm sure that Mercedes and Red Bull have more margin than we have," he told reporters. "So we shouldn't get carried away too much. We'll have one day tomorrow to work hard, and then let's see where we'll end up.

"It's looking good," he grinned. "For now it's looking a bit too good to believe. So let's wait and see. Saturday, we'll know exactly where we are in qualifying, and we'll go from there for the race."

Referring to the second session, he admitted: "I was quite surprised that it ended that way, because Monaco, here especially, it's quite important to do as many laps as we can. Unfortunately with the issue I had in FP1, I had only done four laps. But I felt quite at ease with the car in FP2, and managed to put that lap there."

Asked if he'd been able to use data from his teammate's opening session, Leclerc admitted: "Honestly, on the driver's side, for me, it's nearly impossible to find references with what he's doing, because at the end I don't have my own references. So it's all about basically going out in FP2, trying to take your time to get to speed, trying to take your own references.

"After the first run, I could compare a little bit with Carlos to see where I was lacking. And I just did that for the end of FP2."

If Leclerc's approach comes across as a little 'glass half empty, Sainz is definitely of the 'glass half full' variety.

"We definitely look close to being a genuine threat," said the Spaniard. "We need to wait, we need to wait until FP3. Things change a lot from Thursday to Saturday here, there are some drivers who sandbag a bit on Thursday, just because they want to take it easy. Then, suddenly on Saturday, Lewis always is super quick, so we will see.

"It's nice to see that we are at least closer to the front, that we are playing around at the front," he added. "It's encouraging for the team, there's some positive signs that the car in the corners is not that bad."

Check out our Thursday gallery from Monaco, here.