Piastri said he simply did not have the pace to compete and was 0.366secs off pole.
He said he and McLaren had expected to be able to compete at the front.
“My first lap of Q3 felt reasonable,” Piastri said. “It certainly didn’t feel 0.4secs off. We just didn’t have the pace tonight, which was a little bit of a surprise for us. We were relatively confident going in.”
Piastri’s performance, though, was a return to form for the Australian after a difficult race in Baku, where he made a series of mistakes, culminating in crashing on the first lap.
Starting two places in front of Norris, he has a good chance to extend his 25-point championship lead.
Norris said: “We weren’t quick enough, the Mercedes were quite a lot faster. I didn’t put it all together and you need to do it on a track like this.
“There’s still chances so we have to wait and see.”
Hamilton outqualified Leclerc for the first time since the British Grand Prix to underline an upturn in form in recent races.
He was fastest in the first session and said he felt Ferrari had mismanaged the rest of qualifying.
“The pace was there,” Hamilton said. “We just didn’t optimise the sessions, Q2 onwards.
“I’m definitely more comfortable in the car, this weekend I think I have been driving really well.
“P6 is not good. I definitely think we should have been further ahead but it was all about tyre temp today. It is every week. Tomorrow is going to be tough from where we are. There is not really much we can do from here.”
Williams, whose drivers Alex Albon and Carlos Sainz qualified 12th and 13th, have been reported to the stewards because their rear wings were found to exceed maximum dimensions. This is likely to lead to their disqualification from qualifying.
