Alonso, who won heroically in Valencia last year and produced stirring victories in Malaysia and Hockenheim to finish runner-up to Sebastian Vettel, showed every sign that he will be just as fiercely determined this year.
But he will also have a more competitive car than in 2012, when the driver said Ferrari went into the season "two seconds off the pace".
Alonso, who hands over to his team-mate, Felipe Massa, on Friday for the final day of the second testing session of the year, said afterwards: "With every change we made, the car reacted as I expected and it was useful to try out the different settings, especially to understand which direction we need to go in next week, when there will be a greater emphasis on performance." The teams return to Barcelona next Thursday for the final testing session.
Alonso added: "Once again this year the tyres will be one of the crucial aspects to manage. They are softer and quicker but also less consistent and they degrade rapidly with every lap. We will have a lot of work to do to understand how best to balance the car but that applies to all the teams."
Alonso, who since joining Ferrari has been frustrated in his attempt to add to the two world titles he won at Renault, missed the first testing in Jerez earlier in the month but put in a lap of one minute 21.875sec to finish ahead of Nico Hulkenberg (Sauber) and Romain Grosjean (Lotus), with Nico Rosberg (Mercedes) fourth. Jenson Button was seventh in his McLaren.
Rosberg, Lewis Hamilton's new team-mate this year, said afterwards: "We didn't have a perfect morning and it was tough out there with the low temperatures. They were causing a lot of tyre graining, which made it difficult to do much useful testing.
"In general I'm pleased with what we've achieved this week – I did a lot of mileage and the team has done a good job over the winter. I feel more comfortable in the car and the balance is quite good but we still need to work in a number of areas. That's why I'm looking forward to testing next week and to see what progress we can make."
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