Robert Kubica says his dream of a dramatic return to Formula One is still alive -- seven years after partially severing his right arm in a rally crash -- despite being overlooked by Williams for 2018.

The 33-year-old Pole tested for British team Williams in the hope of landing a full-time seat for the coming season but they instead opted for Russian rookie Sergey Sirotkin to partner Lance Stroll when they announced their line-up on Tuesday.

Kubica's omission from the race set-up has been softened by the role of reserve and development driver, which will see him take part in a number of practice sessions, while he will also be on standby for races.

Kubica took part in three tests for Williams -- he was slower than Sirotkin in the decisive final shootout in Abu Dhabi in November -- and he also drove on a number of occasions for Renault last year.

The French team however, had reservations over the Pole's fitness, particularly the right arm which he nearly had amputated following his rally crash, and opted to sign Carlos Sainz Jr instead.

Kubica, who returned to rallying following his accident in Italy, remained upbeat that his new role was a step towards competing again.

"My ultimate goal remains to race again in Formula One and this (move) is another important step in that direction," said Kubica. "I cannot wait to get started.

"I have enjoyed being back in the Formula One paddock over these past few months, and I now look forward to working with the Williams technical team.

"I feel in the best physical shape that I have ever been, but it has taken a lot of work to get to where I am now, so I'd like to thank Williams for the opportunities they have given me so far, and for putting their faith in me with this appointment."

Kubica, who won the 2008 Canadian Grand Prix, was regarded as one of the finest drivers of his generation before the rally accident on the eve of the 2011 season brought his F1 career to a sudden halt.

He made 76 Grands Prix starts, and finished on the podium 12 times.

Sirotkin gets the nod over Kubica and replaces the retired Felipe Massa to form the most inexperienced line-up on the grid alongside Canada's Stroll, 19.

The 22-year-old Russian, who has twice finished third in the GP2 championship, the feeder series to Formula One, has been a test driver for both Sauber and Renault, but has limited experience.

"To say I'm happy and proud to join such a famous team like Williams is an understatement," Sirotkin said.

"It took a huge amount of work to get where I am, and I'm really happy and thankful to everyone involved."

The announcement by Williams is the final piece in the driver jigsaw for this year's campaign, which gets under way in Melbourne on March 25.

Source: AFP