Sir Alex Ferguson has blamed "one bad week" for costing Manchester United the chance of glory this season.[LNB] United head into Sunday's Premier League encounter with Stoke at Old Trafford knowing they must win to stand any chance of becoming the first team to win four successive titles.[LNB]Even then, the odds are stacked against Ferguson's team given lowly Wigan must also become only the third side this term to take any points off current leaders Chelsea at Stamford Bridge.[LNB]It is an uncomfortable position for United to be in, with the Red Devils acutely aware fate seems destined to conspire against them.[LNB]However, thinking back to where it went wrong, Ferguson has no doubts.[LNB]The week when a home defeat to Chelsea was sandwiched in between the crushing disappointment of a Champions League quarter-final exit to Bayern Munich.[LNB]That desperation lingered into the following weekend, when United failed to overcome Blackburn at Ewood Park, leaving Ferguson and his players to stare at a bleak weekend which is set to leave them empty-handed, with the exception of the Carling Cup.[LNB]"It was a bad week for us and it might have cost us everything," said Ferguson.[LNB]"The biggest disappointment was the European Cup.[LNB]"It is an absolute travesty because we were the better team."