London, Nov 18 (DPA) Andy Roddick withdrew from the season-ending ATP World Tour Finals due to a knee injury he suffered six weeks ago. The US player is being replaced in the eight-man draw by Swede Robin Soderling.

Roddick limped out of the Shanghai Masters with the injury last month. He had earned a berth at the season finale for a seventh straight year - the second-longest active streak after number one Roger Federer's eight consecutive invitations.

Three-time Wimbledon finalist Roddick played the semi-finals in 2003 and 2004 in Houston and 2007 at Shanghai.

Soderling, who beat Rafael Nadal at Roland Garros, was first alternate for the tournament, which begins Sunday at The O2 arena in London. Frenchman Jo-Wilfried Tsonga now becomes first alternate.

Soderling is the first Swede to play the season wrap-up since Thomas Johansson in 2002.

Roddick resumed light practice this week but said Tuesday he would not be fully fit for the tournament.

'I'm really disappointed to miss the World Tour Finals,' Roddick said. 'I love playing in London, and I've heard so many good things about the venue. However, I have not fully recovered from my knee injury, and I won't be able to compete. One of my goals in 2010 will be to qualify for this event again.'

The line-up features Federer, Rafael Nadal, Andy Murray, Novak Djokovic, Juan Del Potro, Nikolay Davydenko, Fernando Verdasco and Soderling.

The draw will be made Wednesday, with the eight players drawn to play a minimum of three round-robin matches to determine which four players advance to the knockout semi-finals Saturday.