The first part of the session saw Red Bull's Sebastian Vettel and Brawn GP's Jenson Button battle for the lead, while soon joined by the two McLaren Mercedes drivers and Barrichello. The Brazilian eventually managed to top the field with 15 minutes to go, after which he made one more attempt to further improve his lap time. Unfortunately, a driving mistake – a stuck gear – prevented him from improving in the late stages of P1.
The top three drivers ended the P1 within two tens of a second, while 4th placed Button finished the morning more than 6 tenths of a second behind his teammate. Vettel had to settle for 5th place, right ahead of Force India's Adrian Sutil.
The German driver managed an outstanding outing on Friday morning, as his VJM02 has been heavily updated ahead of this weekend's race. Williams had one driver in the Top 10 through 7th placed Kazuki Nakajima, who was followed by Mark Webber and Fernando Alonso. Finally, Ferrari's Kimi Raikkonen completed the Top 10, only 0.005 seconds ahead of Toro Rosso's Sebastien Buemi.
As expected, Ferrari's Luca Badoer recorded the very last lap time on Friday morning, finishing the P1 more than 3.3 seconds off the pace from leader Barrichello. This weekend's other debutant Ramain Grosjean, stepping into the R29 for the first time this season, ended the session in 18th place, a full second behind teammate Alonso.
Here are the complete results of the first practice session in Valencia:
1. Rubens Barrichello (Brawn GP-Mercedes) 1:42.460
2. Heikki Kovalainen (McLaren-Mercedes) 1:42.636
3. Lewis Hamilton (McLaren-Mercedes) 1:42.654
4. Jenson Button (Brawn GP-Mercedes) 1:43.074
5. Sebastian Vettel (Red Bull-Renault) 1:43.088
6. Adrian Sutil (Force India-Mercedes) 1:43.209
7. Kazuki Nakajima (Williams-Toyota) 1:43.225
8. Mark Webber Red (Bull-Renault) 1:43.243
9. Fernando Alonso (Renault) 1:43.345
10. Kimi Raikkonen (Ferrari) 1:43.384
11. Sebastien Buemi (Toro Rosso-Ferrari) 1:43.389
12. Robert Kubica (BMW Sauber) 1:43.419
13. Jaime Alguersuari (Toro Rosso-Ferrari) 1:43.637
14. Nico Rosberg (Williams-Toyota) 1:43.746
15. Nick Heidfeld (BMW Sauber) 1:44.040
16. Giancarlo Fisichella (Force India-Mercedes) 1:44.126
17. Romain Grosjean (Renault) 1:44.356
18. Jarno Trulli (Toyota) 1:44.638
19. Timo Glock (Toyota) 1:44.732
20. Luca Badoer (Ferrari) 1:45.840