Scott Dixon kept up his early momentum at Kentucky by topping an ultra-close second session, while there was again little to separate title rivals Dario Franchitti and Will Power.
The 2009 polesitter rose to the top of the timesheets with 15 minutes remaining and was never displaced, as several yellow flags for track debris disrupted the momentum of the session.
Ryan Hunter-Reay (Andretti) moved into second in the final two minutes, following the third and final yellow flag break.
Sarah Fisher's Ed Carpenter, last year's polesitter, finished less than four hundredths down on Dixon in third place. Carpenter was one of eight drivers to lap within one tenth of the ultimate pace.
In that eight were Franchitti (Ganassi, fourth) and Power (Penske, seventh), although both drivers opted to sit out the final two minutes of the session, protecting their hands until qualifying later today.
The pair were separated by Marco Andretti of Andretti and Newman/Haas' James Hinchcliffe, both of whom improved in the closing stages.
Vitor Meira, Dixon's nearest challenger in first practice, ended the second session 16th fastest.
Pos Driver Team Time Gap 1. Scott Dixon Ganassi 24.2587s 2. Ryan Hunter-Reay Andretti 24.2723s + 0.0136s 3. Ed Carpenter Sarah Fisher 24.2930s + 0.0343s 4. Dario Franchitti Ganassi 24.3024s + 0.0437s 5. Marco Andretti Andretti 24.3079s + 0.0492s 6. James Hinchcliffe Newman/Haas 24.3270s + 0.0683s 7. Will Power Penske 24.3302s + 0.0715s 8. Graham Rahal Ganassi 24.3573s + 0.0986s 9. Takuma Sato KV 24.3784s + 0.1197s 10. Danica Patrick Andretti 24.4014s + 0.1427s 11. Helio Castroneves Penske 24.4105s + 0.1518s 12. Oriol Servia Newman/Haas 24.4141s + 0.1554s 13. Ryan Briscoe Penske 24.4216s + 0.1629s 14. Charlie Kimball Ganassi 24.4288s + 0.1701s 15. JR Hildebrand Panther 24.4394s + 0.1807s 16. Vitor Meira Foyt 24.4664s + 0.2077s 17. Ana Beatriz Dreyer & Reinbold 24.4697s + 0.2110s 18. Mike Conway Andretti 24.4806s + 0.2219s 19. EJ Viso KV 24.5050s + 0.2463s 20. Townsend Bell Dreyer & Reinbold 24.5098s + 0.2511s 21. Wade Cunningham Sam Schmidt 24.5108s + 0.2521s 22. Simona de Silvestro HVM 24.5363s + 0.2776s 23. Tony Kanaan KV 24.5416s + 0.2829s 24. Dan Wheldon Sam Schmidt 24.5550s + 0.2963s 25. Alex Lloyd Dale Coyne 24.5856s + 0.3269s 26. Pippa Mann Rahal Letterman 24.6340s + 0.3753s 27. Dillon Battistini Conquest 24.6405s + 0.3818s 28. James Jakes Dale Coyne 24.7732s + 0.5145s