Kimi Raikkonen and Ferrari returned to the top of the timesheet on the final day of 2017's first test - but the session largely proved a damp squib as teams tested Pirelli's new wet tyres in artificially damp conditions.
The searing pace of Day Three was not replicated on Thursday as water tankers twice doused the circuit, first ahead of the morning session and then during the lunch break.
What we learnt from the first week of Testing
As the track dried towards the end of the each session, slick tyres were used with Raikkonen posting a quickest lap on softs of 1:20.872 in the afternoon - his best of the week but just under a second down on team-mate Sebastian Vettel's Wednesday benchmark.
"We've been positive all the time and we've been working well together," Raikkonen said at the end of an encouraging opening week for Ferrari. "It's always exciting to start the year and so far it's been all running pretty smoothly.
"Where we're going to end up in the year, we don't know, but so far it's good."
Lewis Hamilton did not run as scheduled in the morning as Mercedes ran into their first mechanical trouble of the winter, as an electrical fault kept the W08 in the garage for several hours.
Once the problem was fixed late in the morning, Hamilton decided to give what was left of the session over to team-mate Valtteri Bottas with the Finn due in the car for the afternoon in any case.
Bottas still completed 68 laps and finished eighth fastest, with Mercedes ending the week with the quickest overall time and the most number of laps completed.
Max Verstappen posted his best time of the test to take second for Red Bull, with Sergio Perez third for Force India and Stoffel Vandoorne, despite use of the ultrasofts late on, seventh for McLaren.
Jolyon Palmer ended the test third for Renault after a strong late run on soft tyres, with Romain Grosjean fifth for Haas and Sauber stand-in Antonio Giovinazzi fifth.
But Day Four proved a torrid one for Toro Rosso as the Red Bull juniors completed one solitary wet lap with Danii Kvyat. Rooted to the bottom of the mileage charts halfway through the two-test pre-season programme after repeat trouble with their new Renault engine, technical chief James Key said: "The week has been both encouraging but also frustrating with the missed running time.
"However we will now plan our recovery for next week and hope to make up for lost ground!"
The second and final Barcelona test begins on Tuesday March 7.
Day Four Timesheet
1) Kimi Raikkonen, Ferrari, 93 laps, soft tyres, 1:20.872
2) Max Verstappen, 85 laps, soft tyres, 1:21.769
3) Jolyon Palmer, Renault, 39 laps, soft tyres, 1:21.778
4) Romain Grosjean, Haas, 118 laps, supersoft tyres, 1:22.309
5) Antonio Giovinazzi, Sauber, 84 laps, ultrasoft tyres, 1:22.401
6) Sergio Perez, Force India, 82 laps, supersoft tyres, 1:22.534
7) Stoffel Vandoorne, McLaren, 67 laps, ultrasoft tyres, 1:22.576
8) Valtteri Bottas, Mercedes, 68 laps, soft tyres, 1:23.443
9) Nico Hulkenberg, Renault, 51 laps, soft tyres, 1:24.974
10) Daniil Kvyat, Toro Rosso, 1 lap, No time
The second F1 pre-season test starts on Tuesday March 7 and the Sky Sports F1 Digital team will be providing live commentary from dawn until dusk on all four days while Sky Sports News HQ will also deliver live updates from trackside.