Piastri recovered with a strong performance in qualifying – but failed to improve on his last run, and jumped not only Charles Leclerc.
His form in recent races is very different from earlier in the season, when he was out of control, and there is a growing belief that going to the championship can only be in his third season in F1.
“Just feeling things that don’t flow easily, you know?” The 24-year-old said.
“I had a lot of confidence in the car yesterday. It seemed like it was a bit tricker for everyone and just struggled to get out of the car.
“I’ve got the belief that I can go out and win races and win championships but, you know, obviously the things I want don’t come.”
Asked how he can prevent further damage to his title hopes in the race, Piastri said: “Just try and take all the chances I can.
“There is also a little question about what tires to use because, you know, the soft is not good, it is not good in qualifying and it is not good in the sprint.
“So I think there’s a little question mark on that as well and maybe that will give me some opportunities.”
Norris, who was challenged hard for the Sprint Victory by Antonelli, is expected to have an equally strong battle with the 19-year-old Italian in the Grand Prix.
Norris said: “I knew (in the sprint) that they were quick. And I knew that Kimi was pushing at the end.
“So, in some ways I’m looking forward to it, in some ways I’m not. I think it’s going to be a big challenge tomorrow weekend.
Antonelli, who is in his maiden race and has the best result up to third place, said that he hopes that the expected cool conditions will play into the hands of Mercedes.
“The enthusiasm this morning was very strong,” he said. “It’s also cold and tomorrow should be different of the same. So maybe it will help a little.
“But, you know, running in dirty air is not easy. Hopefully, we can have a strong motivation and put pressure on them and hope that we can fight for the victory.”