Arsenal midfielder Mathieu Flamini has admitted that he is "surprised" Chelsea manager Jose Mourinho allowed goalkeeper Petr Cech to be sold to a Premier League rival.

The shot-stopper signed for the Gunners last month for a reported £11m fee.

Cech opted to leave Stamford Bridge following an 11-year spell after becoming second fiddle to number one goalkeeper Thibaut Courtois.

Despite Cech's desire to leave, Flamini has admitted that he would not have predicted that Mourinho would have done business with their London rivals.

"I was surprised by Mourinho because he really doesn't do that," The Telegraph quotes Flamini as saying. "He's a competitor and usually doesn't like to sell any players to his rivals. But it's a good favour for us and now we have to take advantage. It's a top signing. That's why we have been lucky on this one."

Cech is expected to face his former club in this Sunday's Community Shield at Wembley.