"Also, turn five was very tricky for me this afternoon. I think that is the middle sector and then the last sector was better towards the end but still very tricky to find the right balance. It was one of the better sessions this weekend, but still not good enough."
When asked if the car had made any positive steps since the Silverstone double-header, Vettel admitted "it is up and down to be honest."
He added: "There are still some things that I can't really put an answer to.
"I am trying to do everything I can and ignore all the things that might not be right and yeah, do the best that I can. That is all that I can do at the moment."
Leclerc also struggled today qualifying ninth, and the Monegasque pinned his issues to the front-end of the car.
"I am just not happy with the car today," said Leclerc, also to Sky Sports F1.
"At least, this morning I was. The beginning of quali it was okay and then it fell out, session after session in quali and didn't have enough front end to rotate the car. We have lost quite a bit of time because of this."
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