If Mercedes are again quicker at such a benchmark circuit, where the champions have won four times in the last five years, the writing will be on the wall for Ferrari.
On track Bottas looks more committed, more confident and crucially more consistent. "We haven't found the silver bullet - but in the last 10 years I never found the silver bullet so I don't think it exists". "If you work hard it's only a matter of time before things start to go right". "That's good news but in the end it's only Friday and Ferrari is not that far behind... we have to see tomorrow in qualifying when Ferrari turns their new power unit up how they are going to be".
"Certainly we are not happy for the points we have scored so far", Binotto said.
Vettel was blunt in stating there was no silver bullet to solve their problems, only more work to facilitate a greater understanding of their vehicle, but the clock is ticking. "Our objective is not be where we are, so we can not be happy with the start of the season but we have a good vehicle and we are still in the battle". Anything short of a win here would leave them with a mountain to climb. But Hamilton and Bottas were still faster than their Ferrari rivals.
Should they fail to do so and Bottas puts in another winning performance, emphasising his championship credentials, Hamilton's attention will surely shift to his teammate in his bid for a sixth title.
Ferrari team principal Mattia Binotto said even though his team is struggling to catch Mercedes they aren't giving up. "I'm excited by that and encouraged by that". Mercedes team-mate Lewis Hamilton was just half a tenth adrift of Bottas, with Ferrari three tenths down.
Hamilton admitted he found the vehicle trickier to master, having complained of a struggle to get his tyres into the right condition across both sessions.
Roger Federer clinches 1,200th career win at Madrid Open
The Madrid Open is his first clay tournament as he prepares to return to the French Open after a three-year absence. Novak Djokovic continued to play well winning his 13th straight over Jeremy Chardy with a 6-1, 7-6 (2) decision.
Saudi Aramco offers to increase oil supply to India
US West Texas Intermediate (WTI) crude futures were at $62 per barrel, down $0.12, making good on some earlier losses. Brent crude oil futures were at $69.94 per barrel, 6 cents, or 0.1 percent, above their last close.