Bruno Senna admitted that his preparations for the Korean Grand Prix had been hampered by the fact he was forced to sit out the first free practice session of the weekend.
The Brazilian watched from the sidelines for the first 90 minutes of running at Valtteri Bottas took over his car, with Senna then back in action for FP2.
Although he ended the day as the quickest of the three Williams drivers in twelfth spot, Senna admitted it hadn't been ideal to miss the opening session even though he ended the day strongly.
“It was a productive day for me,” he said. “Missing the first session wasn't ideal because I'm not so familiar with this track and my experience here in the last two years has been hampered by rain. But in the end I think we got a good idea of the direction we need to go to improve.
“It's going to be very tough, we can see that in low fuel situations some cars are faster than others, so we need to improve on that, but I'm confident that we can start the race further up the grid.”
Team-mate Pastor Maldonado meanwhile suffered a car problem during the second session which the team will now investigate ahead of Saturday's running.
“As we have seen in previous years the track evolution on the Friday is very big with low levels of grip to start with,” chief operations engineer Mark Gillan said. “We completed a very full combined development and set-up balance optimisation programme with our three drivers.
“We have a few areas to improve on for tomorrow and Pastor also had a car issue throughout FP2, which we are currently investigating.”