Argentine substitute Hernan Crespo scored a stoppage-time winner as champions Chelsea snatched a dramatic 1-0 victory over Wigan Athletic at the JJB Stadium on Sunday.

Chelsea manager Jose Mourinho though was unhappy with the performance of his team and said that the players did not look committed enough.

"They were not pressing hard for the ball; losing it very quickly in the mid-field," said Mourinho.

"Wigan played very well. They showed the right attitude and the right commitment and with the way they played they did not deserve to lose. But sometimes it happens, sometimes when we play well we don't necessarily get the points," he added.

The promoted underdogs, playing their first game in the top-flight, looked destined for a sensational draw until Crespo -- back after a loan spell at AC Milan -- hammered home a superb shot in the 93rd minute.

Chelsea, whose owner Roman Abramovich has spent 330 million pounds ($599.2 million) on the club, deployed all their attacking force on a promoted side who suffered the cruellest of fates.