Valtteri Bottas has been promoted to race driver for the 2013 Formula One season as he will line up alongside Pastor Maldonado at Williams.
Venezuelan Maldonado has retained his seat with the Grove-based marque for a third year, while Bottas, who has been the team's reserve driver for the past two seasons, replaces Bruno Senna.
It had long been suggested Bottas would get his chance in 2013 after impressing in a number of Friday practice sessions this year.
Bottas was GP3 champion in 2010 ahead of his appointment at Williams, where he has played a patient role prior to now being given his long-awaited chance.
Unsurprisingly, Bottas concedes it has been his "lifelong dream to compete in Formula One".
He added: "To do so with one of the most legendary teams in the sport is incredibly special.
"I've really enjoyed my three years with Williams so far and feel very at home here so my goal was always to stay for 2013 and progress to a race seat.
"I'm looking forward to getting my Formula One career started and enjoying a lot of success with Williams."
Founder and team principal Sir Frank Williams has high expectations of Bottas and, after two years of learning and maturing in the wings, has no doubts he can deliver.
Williams said: "In Pastor and Valtteri we have two of the most exciting talents in motor racing and I am especially excited about what 2013 can bring for Williams.
"Pastor has always demonstrated remarkable pace and this year has seen him mature as a racing driver.
"Valtteri is quite simply one of the most talented young racing drivers I have come across and we expect great things from him in the future."
Maldonado endured a turbulent year, from the high of winning the team's first race for seven-and-a-half years in Barcelona in May to the low of several on-track incidents that resulted in a number of trips to the stewards and penalties.
But given his sponsorship from state-owned Venezuelan oil and gas company PDVSA, worth a reputed £27million per year to the team, it is no surprise he has kept his seat ahead of Senna.
Confident of improving further next year, Maldonado said: "I'm really enjoying my time with Williams and I was obviously very happy when I was told I would be continuing with the team in 2013.
"This season was a memorable year for me with the win in Barcelona and we made a big step forward in terms of performance.
"I have a lot of confidence in the team and hopefully next year will see us move even further up the grid and taste more success."
It leaves Senna as the latest driver of renown to now be searching for a seat, with the one at Force India - alongside Paul di Resta - the most highly prized.
In axing Senna, Williams added: "I would like to take this opportunity to thank Bruno for his hard work over the past year and wish him the best of luck going forward."