Zhou Guanyu qualified an impressive fifth for Alfa Romeo at the Hungaroring, split from his team-mate Valtteri Bottas by Leclerc in the Ferrari.
The Monegasque driver's team-mate Carlos Sainz didn't even make it to Q3, ending the Q2 session in 11th place after missing out by just 0.002s.
Asked if he was concerned about the team's pace given he felt he had put on a good lap, he said: "It's not really a concern in the way I feel like it's very difficult to expect the pace of others from qualifying to race, from track to track.
"We've got surprises every weekend, I did not expect to have an Alfa Romeo in front of me for the race tomorrow, so I don't know how they will be in the race."
Regarding Alfa's surge in form, he added: "They were very strong, yesterday the team showed me the simulations of what we think they will be like, and honestly they were alright, the simulation ahead of today.
"And yesterday I was like, 'there might be something wrong in that and it might be a mistake,' and they proved me wrong today because the team expected it.
"Again, we have a lot of work to do. It's very difficult to understand because of my knowledge, I haven't checked, but I don't think they had any particularly big upgrades for this weekend.
Source: Autosport