Chelsea overwhelmed Real Betis 4-0 in the Champions League on Wednesday but exacting coach Jose Mourinho still had cause for complaint.

Asked if he could find fault in a powerful performance, the Portuguese manager criticised his players' poor defending in the air at the start when the Spaniards earned three corners in quick succession in the Group G match.

After competing well against lofty English defenders in their last two domestic games they came unstuck against a diminutive Betis attack.

"I will not accept that we should have had problems in set pieces in the first 20 minutes," Mourinho said.

"To be fair they had a very good start. They were always dangerous until we scored the third goal (after 59 minutes) which killed the game," Mourinho said.

"In the second half they tried but they gave us a lot of space and we scored two more goals where maybe we could have had four or five," he said.

Chelsea sliced open Betis's defence with goals from Didier Drogba [Images] and Ricardo Carvalho in the first half and Joe Cole and Hernan Crespo [Images] after the break.

Asked what message the rout sent to other European hopefuls, Mourinho said he did not want to send messages.

"We just want to achieve our targets and our targets are to win the Premiership and at this moment to be in the next stages of the Champions League," Mourinho said.

"In the Champions League we now have seven points. It's not decided yet but I think we are in a very good position to qualify," he added.

They are top of the group with Liverpool, three points clear of Betis with Anderlecht bottom and yet to gain a point.

Chelsea, whose billionaire owner Roman Abramovich wants the club to dominate in Europe, are already nine points clear at home, having won every Premier League match this season.

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Losing at the semi-final stage for the last two seasons has sharpened their European hunger, however.

Betis coach Lorenzo Serra Ferrer said the match was a learning curve for his side, playing in the competition for the first time.

"We played a great side and it was a big lesson," Serra Ferrer said.

"Chelsea competed better and fought harder on the 50-50 balls. They were more sure of themselves and more decisive in front of goal," he added.

Serra Ferrer was worried about what looked like a serious knee injury suffered by midfielder Miguel Angel who was carried off the field in the second half.

Drogba also left the pitch at halftime limping from a knee injury but Mourinho said it was unlikely to stop the big Ivory Coast striker.

"For some players injury is a drama. For others they have big injuries and they still play. I think Didier is one of those tough boys. I think he will be ready for Sunday."

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