Red Bull's Christian Horner believes the team are very close to the pace set by Mercedes, with Max Verstappen finishing less than a tenth down on the fastest time set by Valtteri Bottas in first practice.
Having had the session interrupted by a red flag, caused by Alfa Romeo's Robert Kubica spinning into the gravel at Turn 10, Verstappen finished just 0.033 down on Bottas' flying lap.
Speaking after the session, Horner highlighted that Mercedes are usually very strong at the Barcelona circuit and took positives from how close Verstappen was to the front.
"It looks like we are very close," Horner told Sky Sport Italia.
"It looks good today, but the red flag was unfortunate for us, so it was not a clean session for us. The gap is only less than one tenth with Mercedes and that at a circuit where Mercedes were very good last year.
"Barcelona is a circuit that has everything and you can see that Mercedes and Red Bull are very close. We are now close today and that is of course very encouraging for us."
Horner also highlighted the ongoing issue of track limits, following comments from Verstappen on Friday urging the introduction of more gravel to line the circuits.
"The fans are having a hard time understanding the track limits, so something needs to be done about that," Horner said.
"I think there will be discussions about that tomorrow. It's difficult to follow because it's different in every corner and that doesn't make it any easier."