Grapevine: Karthikeyan or Kiesa to Williams

The former Jordan and Minardi racers are believed to have been singled-out as the leading candidates to work alongside Mark Webber and Nico Rosberg next year.

Karthikeyan is favourite for the role, thanks to the commitment he showed driving for Jordan this year as well as considerable backing he has from Indian sponsors, although Kiesa may beat him to the job because of his financial situation.

Although Williams technical director Sam Michael has refused to confirm the identity of the candidates for the third driver role, he insisted the final decision about a third driver would be made on technical grounds.

"The key requirement for a third driver is that they are consistent and give good technical feedback," he told Autosport. "Even the ability to learn a track is almost secondary because of the simulations we have.

"I have been surprised by the abilities of some of the guys we have been speaking to."

A final decision about the third driver is expected imminently. Williams are due to resume testing at Barcelona next week with an FW27C chassis that has been modified to take the new Cosworth V8 engine, where it is likely the third driver will be drafted in for his first running with the team.