Kimi Raikkonen may have been quickest in Bahrain practice, however, the Finn reckons his Lotus "didn't feel particularly good" on Friday.
Strapping on the medium compounds midway through the second practice on Friday afternoon, Raikkonen shot to the top of the timesheets with a 1:34.154.
The Lotus driver's advantage, though, was slim as he was just 0.030s up on Mark Webber while both Sebastian Vettel and Fernando Alonso were within two-tenths.
"It didn't feel particularly good today, the car, I think there's improvements to be done," said the 33-year-old.
"The lap time was pretty OK so obviously I made some mistakes - especially in the last corner - so we lost quite a bit of time but hopefully we can improve the feeling a bit for tomorrow so we will see what we can do.
"It's not 100 percent where we want to be but the lap time seems to be more or less there so we have to improve and then I'm sure we can do better lap times."
Raikkonen's running on Friday ended with a long stint on the medium Pirelli compounds.
After 13 laps, asked to push for more from his Lotus team, Raikkonen responded that the tyres had already "gone." He did, however, still put another three laps on the rubber.
Asked whether he was surprised about the tyres lasting so long, he told ESPNF1: "Not really, we do what we feel at the time is the right thing.
"Sometimes the tyres go away and then it's pointless, or your set-up is not right and then it's a bit pointless to run a long run if you know that there's something wrong.
"So today we were just running a bit longer but it depends really how it goes."