Ryan Briscoe was fastest again in the final practice session ahead of qualifying for the IndyCar Series' Long Beach round.
The Australian set a 1m10.322s lap early on, and though his Penske team-mate Will Power kept edging closer, Briscoe stayed ahead by 0.038 seconds.
Ganassi duo Scott Dixon and Dario Franchitti were next up, with Ryan Hunter-Reay again the top Andretti runner in fifth.
A surprise sixth went to Conquest's Sebastian Saavedra, as the young Colombian showed his best IndyCar form so far.
KV Racing Technology had three cars in the top 11, with Tony Kanaan, Takuma Sato and EJ Viso ending up seventh, ninth and 11th respectively, sandwiching Andretti's Marco Andretti and Newman/Haas driver James Hinchcliffe.
The other Newman/Haas car was involved in the only significant incident of the session, as Oriol Servia slid into the Turn 6 barriers in the final few minutes, damaging the front of his Dallara-Honda.
While two Penske drivers led the way, the third car of Helio Castroneves was down in 13th. Ganassi's Graham Rahal also struggled in 15th, and Justin Wilson was only 18th for Dreyer & Reinbold.
Qualifying takes place at 2.25pm local time this afternoon.
Pos Driver Team Time Gap
1. Ryan Briscoe Penske 1m10.3222s
2. Will Power Penske 1m10.3602s + 0.0380s
3. Scott Dixon Ganassi 1m10.5589s + 0.2367s
4. Dario Franchitti Ganassi 1m10.5950s + 0.2728s
5. Ryan Hunter-Reay Andretti 1m10.6509s + 0.3287s
6. Sebastian Saavedra Conquest 1m10.7215s + 0.3993s
7. Tony Kanaan KV 1m10.7390s + 0.4168s
8. Marco Andretti Andretti 1m10.8437s + 0.5215s
9. Takuma Sato KV 1m10.8919s + 0.5697s
10. James Hinchcliffe Newman/Haas 1m10.9184s + 0.5962s
11. EJ Viso KV 1m10.9617s + 0.6395s
12. Oriol Servia Newman/Haas 1m10.9772s + 0.6550s
13. Helio Castroneves Penske 1m10.9899s + 0.6677s
14. Danica Patrick Andretti 1m10.9946s + 0.6724s
15. Graham Rahal Ganassi 1m11.0392s + 0.7170s
16. Mike Conway Andretti 1m11.0491s + 0.7269s
17. Alex Tagliani Sam Schmidt 1m11.0507s + 0.7285s
18. Justin Wilson Dreyer & Reinbold 1m11.0673s + 0.7451s
19. Vitor Meira Foyt 1m11.2257s + 0.9035s
20. Simona de Silvestro HVM 1m11.4465s + 1.1243s
21. Charlie Kimball Ganassi 1m11.5582s + 1.2360s
22. Raphael Matos AFS 1m11.5880s + 1.2658s
23. Sebastien Bourdais Dale Coyne 1m11.6159s + 1.2937s
24. Paul Tracy Dragon 1m11.7337s + 1.4115s
25. JR Hildebrand Panther 1m11.9678s + 1.6456s
26. Ana Beatriz Dreyer & Reinbold 1m12.2099s + 1.8877s
27. James Jakes Dale Coyne 1m12.3638s + 2.0416s