Nico Rosberg kept Mercedes at the top of the times in a second wet Friday practice session for the Brazilian Grand Prix.

Heavy rain before the start of the session left the Interlagos track saturated, contributing to a general dearth of action that prevailed until a frantic final 10 minutes. The initial situation was exacerbated as the rain abated and conditions entered the uncertain window between wets and intermediates, with those who did venture out being warned about overheating problems on their wets.

Such circumstances meant that only six drivers set a time over the opening half hour, while seven drivers ” among them Sebastian Vettel, Fernando Alonso and Lewis Hamilton ” still had to set a time at the hour mark.

For a long while Rosberg’s early 1m28.873s was therefore good enough for top spot, but Alonso helped breathe life into the session when he headed out on intermediates 20 minutes from the end and immediately went third. That provided the encouragement for Felipe Massa, Vettel, Hamilton and the rest of the pack to also emerge on intermediates, with times tumbling as a result.

Sebastian Vettel kicked off the surge when he demoted Rosberg with a 1m27.993s, at the time seven tenths clear of the field. He extended that advantage further, while behind him Webber also improved to move into second and complete a Red Bull 1-2 two minutes from the end.

Rosberg still had time to respond, however, and duly disrupted the Red Bull party by reclaiming top spot with a 1m27.306s. That was more than 0.8sec clear of teammate Hamilton, who clinched fifth on his final flyer. The Briton had earlier spun in the treacherous conditions.

Heikki Kovalainen’s Lotus split Hamilton and the two Red Bulls. Jean-Eric Vergne put his Toro Rosso sixth, fractions ahead of Ferrari’s departing Felipe Massa and Sauber’s Nico Hulkenberg.

Daniel Ricciardo and Romain Grosjean completed the top 10, ahead of Alonso, Esteban Gutierrez and Paul di Resta, back in the Force India after James Calado took over driving duties for first practice.

Pos Driver                Team                   Time       Gap     Laps 1. Nico Rosberg          Mercedes               1m27.306s           12 2. Sebastian Vettel      Red Bull-Renault       1m27.531s  +0.225s  10 3. Mark Webber           Red Bull-Renault       1m27.592s  +0.286s  18 4. Heikki Kovalainen     Lotus-Renault          1m28.129s  +0.823s  13 5. Lewis Hamilton        Mercedes               1m28.147s  +0.841s  9 6. Jean-Eric Vergne      Toro Rosso-Ferrari     1m28.405s  +1.099s  11 7. Felipe Massa          Ferrari                1m28.540s  +1.234s  9 8. Nico Hulkenberg       Sauber-Ferrari         1m28.560s  +1.254s  20 9. Daniel Ricciardo      Toro Rosso-Ferrari     1m28.739s  +1.433s  2010. Romain Grosjean       Lotus-Renault          1m28.891s  +1.585s  1211. Fernando Alonso       Ferrari                1m28.928s  +1.622s  1012. Esteban Gutierrez     Sauber-Ferrari         1m29.049s  +1.743s  1713. Paul di Resta         Force India-Mercedes   1m29.174s  +1.868s  1114. Pastor Maldonado      Williams-Renault       1m29.717s  +2.411s  1315. Adrian Sutil          Force India-Mercedes   1m29.783s  +2.477s  716. Valtteri Bottas       Williams-Renault       1m30.425s  +3.119s  1517. Sergio Perez          McLaren-Mercedes       1m30.748s  +3.442s  818. Jules Bianchi         Marussia-Cosworth      1m31.061s  +3.755s  1819. Giedo van der Garde   Caterham-Renault       1m31.118s  +3.812s  1620. Charles Pic           Caterham-Renault       1m31.165s  +3.859s  1521. Max Chilton           Marussia-Cosworth      1m31.211s  +3.905s  1922. Jenson Button         McLaren-Mercedes       1m31.770s  +4.464s  6