Robert Kubica has enlisted the help of current Formula 1 world champion Nico Rosberg as he looks to return to the sport, amid speculation of interest from Williams.

The Pole has been pushing for a remarkable comeback and would complete three tests with Renault this summer, twice in the 2012 car in Valencia and Paul Ricard before driving the 2017 machine last month in Hungary.

Any hope that return would come with the team he drove with before his infamous rally crash in 2011 would end this week as it was confirmed Carlos Sainz would be joining the French manufacturer's works team on a loan deal for 2018.

It is understood Kubica has asked to be released from the contract that he signed to test with Renault and talks are also believed to be taking place between the 32-year-old and Williams over a 2018 seat, with Felipe Massa's future uncertain.  

Rosberg, who made his F1 debut with Williams in 2006, could well now be involved too as he starts life after the sport following his retirement last year. The German has been linked to Mercedes' upcoming Formula E project but insists his racing days are over. 

Confirming the news, Nico would tweet on Friday: "Excited to be working with Robert and his return to F1. He and Lewis were the fastest I raced against."