Finland's Valtteri Bottas attempted to lower expectation levels after being named as the replacement for Bruno Senna in the Williams Formula One team next season.
Bottas, a test driver for Williams since 2010, will join Venezuelan Pastor Maldonado next season after the British team announced their driver line-up for 2013.
Williams team principal Frank Williams described the 23-year-old Bottas as "quite simply one of the most talented young racing drivers I have come across" in a team statement, saying he expected "great things" from him in the future.
However, Bottas said it might be the second half of next season when he starts to show what he is capable of.
"I had a little factory talk with Frank and I said to him "thanks for the pressure", Bottas said in a conference call.
"Being successful in the future is my own goal and I want to compete against the best in the world and one day be the world champion.
"Pastor is going to be a really strong team mate. It's his third season in the Williams car. If in the second part of the season I can match him or better him it would be really nice but I have a lot to learn."
While he will be a rookie, Bottas will be no stranger to the Williams set-up, having been given the use of Senna's car on Fridays at most of this season's races.
A protege of McLaren's double world champion Mika Hakkinen, he has been groomed by Williams over the past two years and his lap times during practise sessions have turned heads.
"I have been in most of the Friday sessions and that has been perfect preparation and gave me a chance to prove what I could do in the car," Bottas said.
"I'm really happy the team gave me the opportunity for that."
The accident-prone Maldonado was rewarded for winning this season's Spanish grand prix, the team's first race victory since 2004, with a third year at the team.
"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," Williams said in a statement.
"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."
Bottas was even being linked to McLaren as a possible replacement for departing 2008 world champion Lewis Hamilton.
"It has always been my life-long dream to compete in the Formula One world championship," he said.
"To do so with one of the most legendary teams in the sport is incredibly special."