Bruno Senna reckons he needed more track time on the first day of the Korean Grand Prix, after Williams third driver Valtteri Bottas took his seat in the opening practice session.
The Brazilian, who ended the day 12th, is determined to deliver results late in the season with speculation surrounding his position in the team next year.
And while he has driven on the Yeongam circuit twice before - with Lotus last year and HRT the previous season - Senna indicated he would have preferred to get more laps in.
"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," he said.
"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."
Senna, who had a small spin 20 minutes in to the second session near the end of the lap, at least came away from Friday happier than his team-mate Pastor Maldonado, who ended the day 18th fastest.
"It was a difficult day today which means we have a lot of work to do before qualifying," said the Spanish Grand Prix winner.
"The track is quite challenging anyway, but we had some problems in the car this afternoon which we now need to analyse to make sure we can resolve them before tomorrow."
Autosport has produced a standalone special magazine to celebrate our 70th birthday. All current print subscribers will receive a copy for free. To order your copy of the 196-page Autosport 70th Anniversary issue, please go to: autosport.com/autosport70th