Felipe Nasr cut an upbeat figure after spending his first day of testing with Sauber at Jerez on Monday.
Nasr took to the circuit in Sauber's C34 and undertook systems check in the morning prior to focusing on power unit settings and tyre evaluation during the afternoon.
The Brazilian rookie was also able to sample wet weather conditions when a shower hit the circuit during the final hour of running.
"It was a great day," said Nasr, who occupied a reserve role at Williams in 2014.
"I was able to complete a lot of laps, and I was happy with everything I saw. I was getting used to the systems, the procedures and the characteristics of the car.
"It was definitely a good start to understand where we are now. It was important for me to get used to this new environment, but after such a long day, with both dry and wet conditions, I was able to adapt to all the situations. Now we can start working on the details."