Chelsea\'s under-pressure manager Andre Villas-Boas said he wasn\'t thinking of the consequences if they exit the UEFA Champions League for the first time in their history at the group stage on Tuesday, but admitted only they were responsible for the situation they were in. Chelsea - who have reached the final once losing to Manchester United on penalties in 2008 - need to either beat Valencia or draw 0-0 if they are to progress to the knockout stages, otherwise their Spanish rivals will go through at their expense. Villas-Boas, who was brought to Chelsea by Russian billionaire Roman Abramovich at enormous expense after a sensational first season in charge of Porto, conceded that his side had made mistakes during the Champions League campaign. \"We just have ourselves to blame,\" said the 34-year-old, whose side would have been comfortably through already had they not let their concentration wander and throw away winning positions in the away games at Valencia, Genk and Bayer Leverkusen. \"During this campaign of five games, we\'ve done pretty well in terms of performances, but the small details have gone away from us in the last couple of minutes, at Valencia and Leverkusen,\" he said. \"If that hadn\'t happened, we would have been sitting here in a familiar position, like in the past, and, most likely, having qualified.\" However, while Villas-Boas refused to answer questions about his future should they fail to qualify he was insistent that the team was not lacking in confidence. \"It\'s irrelevant what the game represents to me,\" he said. \"Our mindset is to continue in the competition, so we approach the game with maximum care and with confidence for tomorrow (Tuesday).\" Villas-Boas, who guided Porto to the UEFA Europa League trophy, and league and cup double last season, said that his side would not play for the scoreless draw. \"You\'ve seen us play enough to know that we always take the initiative in a game,\" he said. \"Valencia will want to get something because a goal represents a lot to them, and makes things even more difficult for us,\" he added. \"But we will try and take the initiative again and won\'t change our strategy.\"