WILLIAMS F1 driver Valtteri Bottas is on the verge of joining Mercedes with Felipe Massa set to return to the sport as his replacement.

The 27-year-old Finn is close to completing a move to become Lewis Hamilton's teammate for 2017.

As a result, it has been reported Grove-based Williams are on the verge of bringing back Massa, who had announced his retirement from F1, for at least a year.

Bottas would replace world champion Nico Rosberg, who left the sport last month due to personal reasons, with the deal set to be completed in the new year.

It was also announced today Williams' chief technical officer Pat Symonds is to step down from his role.

The 63-year-old has been with the Oxfordshire team since 2013, but will leave at the end of the year.

Symonds joined Williams from Virgin Racing, helping the team to third in the constructors championship in his first full year in 2014.

Deputy team principal Claire Williams said: "Pat has been a tremendous asset to this team over the past three years.

"Pat's appointment was the start of a major restructuring exercise, and he has been pivotal in reshaping Williams into what is a much stronger racing team today.

"I would like to thank him for all of his hard work and commitment during that time. We now look to the future and will be announcing details regarding the team's technical leadership in due course."