00:10Darts: World Championships - Extra2011Day 4BBC Two Duration: 2 hours Wed 5th Jan 2011, 00:10 on BBC Two EnglandRob Walker introduces action from day four, where second round matches are under way.ContributorsPresenter:Rob WalkerCommentator:Tony GreenCommentator:David CroftCommentator:Vassos AlexanderGenresSportDartsBrandDarts: World Championships - ExtraSeriesDarts: World Championships - Extra: 2011 Source: BBC Online