Sebastian Vettel has a few concerns about Red Bull's qualifying pace in Monaco after failing to run at the front in practice.
While the Mercedes and Ferraris dominated Thursday's two practice sessions, Red Bull struggled throughout the day.
Vettel finished tenth in FP1, 1.185s down on the soft tyres, while later in the day, using the supersoft rubber, he was ninth. This time around he was 1.255s off the pace.
"All in all it was okay, but unfortunately we had to make a big change and we lost quite a lot of time in the afternoon," said the reigning World Champion.
"Not completely ideal but that's Friday - or in this case Thursday.
"We'd like to be more competitive in low-fuel configuration, so we need to try and find some lap time there."
He added: "My run on super-soft was very poor and we need to understand why.
"I wasn't able to improve and we should be able to quite easily so we need to have a look."
But while his single lap pace was lacking, the Championship leader believes his RB9 is showing good race pace.
"I did a long-run on supersofts and it seemed quite okay."