Robert Kubica appears to have lost out in the race for a 2018 F1 seat but Williams have refused to comment on widespread reports that Sergey Sirotkin is set to take up the vacancy.

Felipe Massa was Lance Stroll’s team-mate last year after being rushed out of retirement to replace Mercedes-bound Valtteri Bottas.

But the Brazilian has retired for good this time and Williams have explored a number of options to replace him, including former F1 driver Kubica and Renault reserve driver Sirotkin.

Both tested for the Grove-based outfit in Abu Dhabi after the last race of the season and Kubica set the faster times on the ultra-soft tyres.

However, reports emerged yesterday suggesting that Williams had decided against signing Kubica with a £15million sponsorship package behind Sirotkin said to be playing a major role.

But the team have remained silent on the rumours while Sirotkin's manager, Gianpaolo Matteucci, would only talk up his driver’s skill and refused to comment on the contract situation.

“Surely Sergey is a strong, talented candidate for that place,” Matteucci said.

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Daniel Ricciardo has been given the hurry-up by Red Bull over his contract talks.

The five-time Grand Prix winner has just 12 months remaining on his current deal and has reportedly been courted by both Mercedes and Ferrari.

The Australian is thought of as one of the grid’s very best overtakers and has twice finished third in the F1 World Drivers’ Championship.

But Red Bull boss Christian Horner has warned Ricciardo, whose team-mate Max Verstappen signed a new contract earlier this year, that there are other drivers the team would happily sign.

"I think Daniel knows what our strengths are and hopefully we’ll be in a reasonable position," Horner told Racer.

"I think he’s at a stage in his career where he’s wanting to evaluate all of his options, which you can understand.

"The problem is we won’t wait around forever and we’ve got some very good options available to us, but our priority is to try and ensure we find a solution with Daniel."

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Mercedes have continued their strategy of recruiting the best people in the business by picking up former Ferrari man Lorenzo Sassi.

Sassi was the chief engineer in Ferrari’s engine development department but left the team in July with sources on Italy claiming the departure came as a result of an intervention by president Sergio Marchionne, who denied the allegations at the time.

"Sassi is continuing the development of his career,” Marchionne said.

And now Sassi is reportedly ready to join reigning F1 champions Mercedes ahead of the 2018 season.

Mercedes made a similar move for British engineer James Allison, who ended a three-year spell with Ferrari in the summer of 2016.

But he was back on the grid just seven months later, taking over from Williams-bound Paddy Lowe as technical director at Mercedes.