With the start of opening Friday practice for the 2011 Spanish Grand Prix the AT&T Williams F1 team would continue their development of new parts for their FW33. They were continuing testing the new specification rear wings. On his installation laps flow-vis paint was applied to the rear wing of Barrichello's Williams prior to him leaving the garage. The weather was warmer than at the preseason test so the teams would be looking to assess their new developments for their cars. Pastor would run with the old rear wing to allow the team to compare performance. Pirelli had brought a new hard tyre to this race which help with the issue of tyre degradation.

Schumacher had set the fastest lap in pre-season testing here with a 1m:21.268 on the final dry day of the pre-season. With twenty five minutes of the session completed Pastor had taken to the track while Rubens was still in his garage. Pastor's first time was a 1m:31.958, a time of little meaning as the Williams team continued to gather data off the FW33. With just about forty five minutes of the session completed Rubens would take to the track for his first serious runs of the session. He would move into the top ten with a 1m:27.899.

With forty minutes of the session remaining Rubens would improve to move up to eighth with a 1m:27.212. Webber was currently fastest, 1m:25.142, from Rosberg and Alonso. Vettel was in fourth followed by Hamilton, Heidfeld, Button, and Rubens. Rubens had pitted while Pastor continued out on the track. Pastor's time was a 1m:28.005. But again Pastor would get it wrong spinning his car slowly off the track and into the gravel at Turn twelve. It looked like when he ran wide he list grip seeing him take to the gravel. His car was stuck and his session was over as his car was lifted away by the marshals. Both Red Bull cars were out on the track with Vettel been told not to use his KERS.

Vettel was now third with a 1m:26.400 with Alonso fourth followed by Hamilton. Vettel's next lap would see him move up to second with a 1m:26.149. Rubens was back out on the track while Webber had pitted. Pastor had now dropped to twelfth as both Red Bull cars were back in their pits, joined by Rosberg. Rubens would pit after a short run with just under fifteen minutes remaining. Pastor would say that he lost the rear end of the car but he felt nothing was damaged on his car. Webber was back out along with Button who was currently in seventh. Vettel would join him as Rubens had dropped to ninth and Pastor was still twelfth. With seven minutes remaining Rubens was back out as Schumacher moved up to eighth with a 1m:27.193.

Perez was up to fifth with a 1m:26.954 followed by Hamilton, Schumacher, Heidfeld, Button, and Rubens now in tenth. Pastor would drop to thirteenth with Ricciardo now twelfth. As the final few minutes counted down the track was very busy with just a few cars still in their garages. Rubens had completed nineteen laps as the session came to an end. Pastors car was now back in the pits with his mechanics having to check his car prior to the next afternoon session. Webber would remain fastest with a 1m:25.142 from Vettel, Rosberg, Alonso, Perez, Hamilton, Schumacher, Heidfeld, Button, and Rubens in tenth.

Early days for the Williams team as they work through their schedule. But Pastor's loss of track time was not something that the team had hoped for but at least his car was not damaged.

Pos  Driver          Team		   Time       Laps
 1.  M Webber        Red Bull-Renault      1m25.142s  27 
 2.  S Vettel        Red Bull-Renault      1m26.149s  20
 3.  N Rosberg       Mercedes              1m26.379s  29
 4.  F Alonso        Ferrari               1m26.480s  27
 5.  S Perez         Sauber-Ferrari        1m26.738s  26
 6.  L Hamilton      McLaren-Mercedes      1m26.988s  19
 7.  M Schumacher    Mercedes              1m27.016s  32
 8.  N Heidfeld      Renault               1m27.132s  21
 9.  J Button        McLaren-Mercedes      1m27.138s  22
10.  R Barrichello   Williams-Cosworth     1m27.212s  20
11.  V Petrov        Renault               1m27.241s  22
12.  D Ricciardo     Toro Rosso-Ferrari    1m27.471s  23
13.  P Maldonado     Williams-Cosworth     1m28.005s  11
14.  N Hulkenberg    Force India-Mercedes  1m28.027s  26
15.  A Sutil         Force India-Mercedes  1m28.163s  22
16.  F Massa         Ferrari               1m28.654s  28
17.  K Kobayashi     Sauber-Ferrari        1m28.819s  23
18.  J Alguersuari   Toro Rosso-Ferrari    1m28.995s  9
19.  H Kovalainen    Lotus-Renault         1m29.231s  21
20.  J D'Ambrosio    Virgin-Cosworth       1m30.896s  18
21.  T Glock         Virgin-Cosworth       1m31.235s  24
22.  T Liuzzi        HRT-Cosworth          1m31.268s  23
23.  J Trulli        Lotus-Renault         1m31.418s  12
24.  N Karthikeyan   HRT-Cosworth          1m32.106s  25