Williams believes Logan Sargeant has grown into the role of being an F1 driver since they announced he would be replacing Nicholas Latifi in November last year.
Originally the team planned to run Sargeant for two years in Formula 2, before the American was fast-tracked following his performances in the F1 feeder series.
Head of Vehicle Performance, Dave Robson, highlighted how the American was "timid" when he was first working with the team but has quickly adapted to becoming an F1 driver following the post-season test in Abu Dhabi.
"I think he's progressed really well. Obviously, it was good to be able to get him in the car in Abu Dhabi at the end of season test," said Robson.
"I think that was a really good opportunity for him to work properly with the engineers and to get time in the car, and a good opportunity to run the tires. I think he's changed and improved a lot, he's grown up a lot it would be fair to say.
"When we first met him, he was quite timid. Now he's starting to sound like a proper F1 racing driver. He's now demanding as he should be, he's got his big team of engineers he has been working with over the winter."
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Robson: Sargeant quick against Albon at Abu Dhabi test
Sargeant took part in the post-season test in Abu Dhabi where he posted the seventh quickest time, within a tenth of teammate Alex Albon.
Robson said he believed Sargeant did an "extremely good job" to get close to Albon, but still thinks the American has a lot to learn when it comes to tyre management.
"I think he did a he did an extremely good job in Abu Dhabi, he was quick against Alex and he didn't put a foot wrong," explained Robson.
"He's got quite a lot to learn when it comes to managing the tyres whilst also racing. We did a reasonable amount of tyre management work with him in Abu Dhabi, but clearly he was largely on his own on the track.
"It's not the same as actually, physically racing cars around - you will be under pressure. So that's something he's got to learn and develop."