Mercedes' Toto Wolff has said the team have '24 hours to screw it up', after topping both practice sessions on Friday.
Lewis Hamilton led the way on Friday afternoon, a tenth clear of teammate Valtteri Bottas to give Mercedes a one-two finish as Red Bull had a strangely subdued session.
Speaking afterwards, Wolff said it's the best Friday his team have managed so far this season.
"That was good. I think it was all our best Friday so far," Wolff explained to Sky Sports F1.
"So pretty encouraging. And we just discussed on the pitwall 'so we have 24 hours to really screw it up'."
With the Barcelona circuit usually a good gauge of how good a car really is, thanks to its varied nature of corners and car demands, Wolff said the lack of usual pre-season testing at the venue hasn't prevented the team from hitting the ground running for this year's race.
"I think we have the data from the previous year," Wolff said.
"Nevertheless, everybody says that Barcelona is also representative of the track. The question is whether it still really is. You know, there's plenty of tracks that have all kinds of corners and straight. So this one is good to represent the difficulty in the last sector which is hard against the tyres, but the rest..we'll see."