The father of Sergey Sirotkin, Williams new recruit, says his son secured the coveted seat because he was "stronger" than Robert Kubica during testing in all areas.
The 22-year-old Russian popped up on the scene as a surprise contender for the 2018 Williams drive alongside Lance Stroll, but ultimately performed beyond expectations when the Grove-based outfit pitted Sirotkin against Kubica at the team's post-season test in Abu Dhabi in November.
Sirotkin's father Oleg says Williams' decision is a reflection his son's ability and performance.
"Sergey proved to be stronger than Kubica in testing, both in qualifying and racing mode," he told the Tass news agency.
"Sergey was also tested on the simulator where he demonstrated very good knowledge. He gives feedback above the level of other young drivers before him," he added.
As Williams boasts the youngest line-up on the grid, and the youngest in its forty-year history, many question whether Stroll and Sirotkin will be up to the task of delivering a competitive year.
"The task is to keep the team's fifth position, because the situation is now more complicated," said Oleg Sirotkin.
"McLaren is going to Renault engines and they have always produced one of the best chassis. Renault has been preparing its car for this season for about two years, so they will also be faster, so the competitors will be Force India, Renault and McLaren," he said.
"I think Williams has good potential for growth," concluded Sirotkin Snr.
"Yes, they have young drivers now, but in a year or two they will be even stronger."
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