Dan Ticktum admits that he was annoyed after missing seven or so tenths during his last fast lap due to an issue with the tyres.
However, the Briton admitted that he understands the test was not about lap times, as Red Bull concentrated on gathering data to help improve the RB15, which struggled during the Bahrain Grand Prix.
Ticktum ended the day 1.8 seconds down on George Russell in the Mercedes, but managed to clock 135 laps for the energy drink - the second most of any driver during the two days of testing.
“I think we got some really good data for the team which is obviously the most important part of these days,” Ticktum said. “I had a little issue on my last tyre run which stopped me from going about seven or so tenths faster.
“I’m a little bit annoyed about that but it’s not what this day is about, it’s about gathering data. In that respect it’s good."
Ticktum added that his fitness faced no issues during the test, as he has been preparing for months.
“Fitness is absolutely fine. I’ve prepared quite a lot since January. The last three or four months have been pretty flat out and that’s helped. The neck wasn’t too bad either.”
The 19-year-old admitted that the step up to F1 was very big, and that the series is much more complex than Super Formula, the series he's currently competing in over in Japan.
“A lot was learned as it was my first time in a modern F1 car,” he said. “It was a big step up for me, even from Super Formula. The biggest thing for me was learning about all the different procedures because you don’t have that in the junior formulas.
“All the different things on the steering wheels, even on push laps you have to change so many things. That was all a bit to take in to start with but I think I got used to it pretty quickly.
“It’s a bit heavier than Super Formula so you notice that in the slow-speed corners. Everything else is much better obviously.”