Former Renault reserve Sirotkin, who is backed by Russian programme and reportedly brings a financial package worth around £15million, emerged as favourite to replace Felipe Massa in the Grove-based team following a strong showing in the Abu Dhabi test.

Robert Kubica, Paul di Resta, Daniil Kvyat and Pascal Wehrlein were among the other contenders for the drive.

"We selected him as the best driver available to us, bar none," Lowe told Motorsport.com.

"We're confident that he will be very quick, very consistent, very calm in his working - and I think these qualities will take him a long way, to do really well in this championship."

Sirotkin and teammate Stroll will make up one of the least experienced pairings on the 2018 grid, with only the Toro Rosso pair having fewer combined grand prix starts.

Lowe, however, rejected the suggestion that Williams' choice of line-up was a gamble.

"I wouldn't describe it as a gamble. We understand that there are some disadvantages. I guess, for Sergey, there is a learning curve around that first year, particularly with some of the circuits he hasn't been to before.

"But, you know, his performance stands in its own right."

He added: "At the same time, we're investing - one of the advantages of a younger driver is, if it's a great driver, you're investing in a long-term future and a long-term success that that can bring to him and to the team.

"So I think we prefer to see that in Sergey we found a rising star, and we hope to work with him in the long-term and enjoy a lot of success together."

Stroll and fellow 2017 rookie Stoffel Vandoorne both struggled against their vastly more experienced teammates during the early races of the campaign – but Lowe believes there is no reason why Sirotkin should endure a difficult start this year.

"We don't want to drive too much expectation, but we're confident that Sergey will drive well, he's shown himself able to do that, in our car and also in series in the past.

"I mean, he was the best rookie in his first season in F2 [GP2], he came third, that was the best rookie result of that year. I think that stands as a good example of what he can do."

Lowe admitted that being an F1 rookie was "certainly not easier" now than it had been in the past, but backed Sirotkin to adapt quickly.

"The tyres are more difficult, and these cars are performing at the peak levels ever seen in the sport, so that must add its challenges.

"But at the same time, we saw what Sergey can do in the car when we put him in there in Abu Dhabi, and those features didn't seem to let him down at all, didn't seem to hold him back, so we're confident he'll do a great job."