Mirko Bortolotti says he could have gone faster in Yas Marina test but for a late red flag

The 21-year-old Italian, who was driving for Williams as a prize for winning this year's Formula 2 crown, ended the day seventh fastest, but had to abort a run with 10 minutes remaining when Sauber driver Esteban Gutierrez spun and triggered a red flag.

"It's a bit disappointing," Bortolotti said. "Every time you jump in the car, you want to be quick. But even with the red flag we did well, so it's not a big deal.

"But it didn't help us because that was when we were out on new tyres and could have improved our performance."

Bortolotti, who has previously tested Toro Rosso and Ferrari machinery, was content with his performance on his F1 test return.

He completed a total of 74 laps, posting a time 4.360s off pacesetter Jean-Eric Vergne (Red Bull) and was able to improve his pace throughout the day.

"I'm very happy with the job that we did," he said. "We had no dramas, the team did a really good job and the performance was good.

"In the afternoon I could start doing proper runs, start to find the performance, the right braking points and lines on a track that you don't know."

Bortolotti believes that his test performance proves that he is now ready to step up to F1.

"That's the main target," he said. "You never know motor racing, let's see what happens.

"It depends on so many factors. If it was up to me, I would say I'd like to do it, but we have to see if it is possible. There are so many factors in play."