(REUTERS) - Finland's Heikki Kovalainen will replace compatriot Kimi Raikkonen at Lotus for the last two races of the season, the Formula One team said at the United States Grand Prix on Thursday.

Raikkonen, currently third in the championship, announced on Sunday he would be missing the races in Austin and Brazil because he needed back surgery.

"Jumping into a car so late in the year when you have not been competing in the races all season will be a challenge, but I know the team at Enstone well so I have no concerns about getting up to speed," said former Renault driver Kovalainen.

In another development, Danish driver Kevin Magnussen will replace Mexican Sergio Perez at McLaren next season, the team said in a statement.

"We're delighted that Kevin will be joining Jenson (Button) as a McLaren Formula One race driver for 2014," said team principal Martin Whitmarsh.

The 21-year-old, son of former McLaren and Stewart racer Jan Magnussen, will be the first rookie to make his F1 debut with McLaren since Britain' Lewis Hamilton in 2007.