Saturday practice for the 2013 Brazilian Grand Prix would again see the Williams F1 team facing further wet track conditions with rain continuing to fall. With the start of the session it would be Gutierrez out first with both Williams drivers also coming out. The rain was expected to fall for at least the first fifteen minutes of the session. Both Williams drivers were on the full wet tyre as Gutierrez set a 1m:34.837 to record the first time. Both Williams drivers would pit after one lap having checked the conditions. More drivers would come out including Vettel, Van der Gar, and Hulkenberg. A 1m:34.671 from Gutierrez on his second lap as Grosjean came out for a single lap. Gutierrez continued to put in laps improving with a 1m:34.129.

Webber would complete his single installation lap followed by the Mercedes cars of Hamilton and Rosberg. Next out were Alonso and Perez. The teams were focusing on their tyre usage with only a limited number of wet and intermediate tyres available. Gutierrez would finally pit after seven laps. Only the Torro Rosso's had yet to come out with over fifteen minutes of the session completed. Hamilton was back out on the track with reports saying that the Williams team had changed to a wet setup from their essentially dry setup that they ran Friday. There was little action on the track with all the teams careful about using their tyre allocation. With thirty minutes remaining Hulkenberg would return to the track joined by Chilton and Bianchi with the rain having eased. A 1m:36.654 from Chilton as Hulkenberg pitted.

Valtteri was back out for Williams running on full wets as Bianchi set a 1m:33.412 to be quickest. Van der Gar and Vettel would also take to the track joined shortly after by Pic and Perez. Valtteri would set a 1m:32.772 to move to the top of the times as Bianchi and Chilton pitted. Vettel would go fastest in sector one as both Hamilton and Rosberg would leave the pits. A 1m:31.857 from Vettel to be 0.515 ahead of Valtteri. Valtteri had improved his time with a 1m:32.372 to remain second. Perez was now third with a 1m:32.731 with Bianchi now fourth. Van der Gar was fifth followed by Gutierrez and Pic. Pastor was now back out joined again by Hulkenberg. Gutierrez would go fastest with a 1m:31.121 with Vettel having pitted. Valtteri was now fourth and Pastor sixth with a 1m:32.849. Hamilton would go fastest with a 1m:29.980 with Hulkenberg now third, 1m:31.452.

More drivers were out on the track with sixteen minutes left in the session as Pastor improved with a 1m:32.195 to be sixth with Valtteri now seventh and back in his pit. Pastor would also pit after his short run as Ricciardo took to the track. Nine drivers had yet to set a time with fourteen minutes remaining. Gutierrez had completed thirteen laps the most of any one. Sutil was now fourth with a 1m:31.610. The order was Hamilton from Gutierrez, Hulkenberg, Sutil, Vettel, Pastor, Valtteri, Perez, Van der Gar and Bianchi tenth. Webber would come out being the first to do so on the intermediate tyre. With ten minutes remaining Pastor would come back out for his next run. Valtteri was also back out as Webber went fastest with a 1m:29.493. His next lap would see him go fastest in sector one and two. He would finish his lap setting a 1m:27.891 as other drivers also found pace.

Valtteri was now second with a 1m:28.600 with Hulkenberg and Kovalainen third and fourth. Pastor was now fifth with a time of 1m:29.686. Pastor would pit with Grosjean now eighth with all the quicker times being set on the intermediate tyre. The final minutes would count down as Kovalainen went second fastest with a time of 1m:28.595 but he would be beaten by team-mate Grosjean with a 1m:28.195 seeing Lotus second and third. Valtteri and Pastor were fourth and sixth. Gutierrez would improve to be sixth and Vergne now seventh. As a result Pastor had dropped to eighth. Di Resta was now tenth as the session came to a close. Neither Ferrari had set a time along with Rosberg and Button. Vergne was now sixth and Gutierrez now seventh. Di Resta and Sutil were ninth and tenth.

With the changing track conditions it was very hard to draw any real conclusions as to the performance of the Williams drivers despite having seen both Williams drivers in the top ten with Valtteri fourth and Pastor eighth. But several drivers had saved their tyres in the session which should give them an advantage in qualifying.

Pos  Driver         	  Team		        Time     Laps
 1. Mark Webber           Red Bull-Renault      1m27.891s 5
 2. Romain Grosjean       Lotus-Renault         1m28.195s 5
 3. Heikki Kovalainen     Lotus-Renault         1m28.595s 6
 4. Valtteri Bottas       Williams-Renault      1m28.600s 12
 5. Nico Hulkenberg       Sauber-Ferrari        1m28.830s 15
 6. Jean-Eric Vergne      Toro Rosso-Ferrari    1m28.921s 5
 7. Esteban Gutierrez     Sauber-Ferrari        1m29.215s 21
 8. Pastor Maldonado      Williams-Renault      1m29.686s 10
 9. Paul di Resta         Force India-Mercedes  1m29.736s 6
10. Adrian Sutil          Force India-Mercedes  1m29.913s 8
11. Lewis Hamilton        Mercedes              1m29.980s 8
12. Daniel Ricciardo      Toro Rosso-Ferrari    1m29.988s 9
13. Jules Bianchi         Marussia-Cosworth     1m30.635s 9
14. Charles Pic           Caterham-Renault      1m30.837s 14
15. Max Chilton           Marussia-Cosworth     1m30.972s 10
16. Giedo van der Garde   Caterham-Renault      1m31.154s 14
17. Sebastian Vettel      Red Bull-Renault      1m31.$57s 4
18. Sergio Perez          McLaren-Mercedes      1m32.731s 4
19. Nico Rosberg          Mercedes              no time   4
20. Fernando Alonso       Ferrari               no time   2
21. Jenson Button         McLaren-Mercedes      no time   1
22. Felipe Massa          Ferrari               no time   2