Nico Rosberg set the fastest time of the week in Formula 1 testing in Bahrain, as reigning champion Red Bull suffered another torrid four days of pre-season running.
Rosberg topped the final day of the test, during which Mercedes-engined teams dominated the timesheets.
Force India's Nico Hulkenberg and McLaren's Kevin Magnussen set the pace across the first two days, before Lewis Hamilton and Rosberg each took a turn to lead the way for the works team.
Rosberg's final benchmark of 1m33.283s put him within a second of his own pole time from last year's race at the same venue.
However, the team did find a number of issues with the F1 W05 over the course of the test, showing that even the more comfortable teams are not immune to the difficulties of mastering this new formula.
|Bahrain test reports|
|Hulkenberg fastest on Bahrain day one|
|Magnussen puts McLaren on top on day two|
|Hamilton fastest, Red Bull woes continue|
|Rosberg keeps Mercedes ahead as test ends|
While there were plenty of positives for the four Mercedes-powered squads (Williams was so advanced in its programme that it spent day three doing pitstop practice, while McLaren set top-four times on each day with Magnussen and Jenson Button driving), there was more disquiet at Renault outfit Red Bull.
The team suffered problems with its RB10 throughout the test, limiting Daniel Ricciardo and world champion Sebastian Vettel to a combined total of 116 laps, with a best lap time of 1m39.837s set by Ricciardo on the final day.
By contrast, Rosberg's best lap time of the week was over 6.5 seconds faster, while Mercedes completed a grand total of 315 laps between its two drivers.
The other Renault-powered teams encountered plenty of difficulties too.
Lotus looked in deep trouble early on, and Romain Grosjean cut a dejected figure in the paddock during the first two days.
But 59 laps for Pastor Maldonado on the final day (which still featured plenty of technical issues) gave the team cause for greater optimism.
"Major" technical problems for Toro Rosso, and Caterham only logging decent mileage by turning the engine down on days one and three, made for many a furrowed brow among the other teams using Renault propulsion.
Meanwhile, Ferrari completed a solid if unspectacular amount of running with Fernando Alonso and Kimi Raikkonen.
|AUTOSPORT columns from Bahrain|
|Red Bull crisis continues in Bahrain|
|Is Lotus running out of time?|
|F1 2014 is not too slow|
|Light at the end of the tunnel for Renault|
The Scuderia amassed nearly 300 laps across four days, despite a telemetry issue restricting Raikkonen to just 44 laps on Friday before he crashed the car at the end of the final day.
Apart from Esteban Gutierrez (who racked up 151 laps and set the eighth fastest time of the test), drivers in the Ferrari customer teams endured a difficult test.
The Mexican's team-mate Adrian Sutil clocked 82 laps on day one, but only seven on the final day, when the Swiss team discovered a chassis problem on the C33.
Marussia arguably endured the worst test of all the teams, completing less than 30 laps across four days, thanks to IT, engine and fuel system difficulties.
Combined times: Pos Driver Team Time Gap 1. Nico Rosberg Mercedes 1m33.283s 2. Lewis Hamilton Mercedes 1m34.263s +0.980s 3. Kevin Magnussen McLaren-Mercedes 1m34.910s +1.627s 4. Jenson Button McLaren-Mercedes 1m34.957s +1.674s 5. Nico Hulkenberg Force India-Mercedes 1m36.445s +3.162s 6. Fernando Alonso Ferrari 1m36.516s +3.233s 7. Kimi Raikkonen Ferrari 1m36.718s +3.435s 8. Felipe Massa Williams-Mercedes 1m37.066s +3.783s 9. Esteban Gutierrez Sauber-Ferrari 1m37.180s +3.897s 10. Valtteri Bottas Williams-Mercedes 1m37.328s +4.045s 11. Sergio Perez Force India-Mercedes 1m37.367s +4.084s 12. Felipe Nasr Williams-Mercedes 1m37.569s +4.286s 13. Pastor Maldonado Lotus-Renault 1m38.707s +5.424s 14. Daniil Kvyat Toro Rosso-Renault 1m38.974s +5.691s 15. Daniel Ricciardo Red Bull-Renault 1m39.837s +6.554s 16. Kamui Kobayashi Caterham-Renault 1m39.855s +6.572s 17. Sebastian Vettel Red Bull-Renault 1m40.224s +6.941s 18. Adrian Sutil Sauber-Ferrari 1m40.443s +7.160s 19. Jean-Eric Vergne Toro Rosso-Renault 1m40.472s +7.189s 20. Romain Grosjean Lotus-Renault 1m41.670s +8.387s 21. Marcus Ericsson Caterham-Renault 1m42.130s +8.847s 22. Max Chilton Marussia-Ferrari 1m42.511s +9.228s 23. Robin Frijns Caterham-Renault 1m42.534s +9.251s 24. Jules Bianchi Marussia-Ferrari no time Distance by driver Pos Driver Team Laps Km 1. Nico Rosberg Mercedes 174 941 2. Valtteri Bottas Williams-Mercedes 171 925 3. Jenson Button McLaren-Mercedes 169 914 4. Fernando Alonso Ferrari 161 871 5. Esteban Gutierrez Sauber-Ferrari 151 817 6. Lewis Hamilton Mercedes 141 763 7. Nico Hulkenberg Force India-Mercedes 137 741 8. Kevin Magnussen McLaren-Mercedes 127 687 9. Kimi Raikkonen Ferrari 126 681 10. Marcus Ericsson Caterham-Renault 102 552 11. Adrian Sutil Sauber-Ferrari 89 481 12. Felipe Nasr Williams-Mercedes 87 470 13. Pastor Maldonado Lotus-Renault 85 460 14. Kamui Kobayashi Caterham-Renault 83 449 15. Jean-Eric Vergne Toro Rosso-Renault 77 416 16. Sergio Perez Force India-Mercedes 76 411 17. Sebastian Vettel Red Bull-Renault 73 395 18. Robin Frijns Caterham-Renault 68 368 19. Felipe Massa Williams-Mercedes 65 351 20. Daniil Kvyat Toro Rosso-Renault 62 335 21. Daniel Ricciardo Red Bull-Renault 43 232 22. Romain Grosjean Lotus-Renault 26 140 23. Max Chilton Marussia-Ferrari 21 113 24. Jules Bianchi Marussia-Ferrari 8 43 Distance by team Pos Team Laps Km 1. Williams 323 1748 2. Mercedes 315 1704 3. McLaren 296 1601 4. Ferrari 287 1553 5. Caterham 253 1369 6. Sauber 240 1298 7. Force India 213 1152 8. Toro Rosso 139 752 9. Red Bull 116 627 10. Lotus 111 600 11. Marussia 29 156 Distance by engine manufacturer Laps Km 1. Mercedes 1147 6207 2. Renault 619 3350 3. Ferrari 556 3009