Chelsea responded with an immediate £6 million bid for the Stoke City goalkeeper Asmir Begovic but Abramovich's decision to let Cech join Arsenal, which conflicted with Mourinho's publicly stated wish, is the source of controversy around Stamford Bridge.

Arsenal have struggled with the goalkeeper position during recent seasons but Cech - regarded by both Mourinho and Arsene Wenger as one of the best in the world - will now report for training at the club's London Colney base next Monday. He has signed a four-year deal worth more than £100,000 a week and his first match should be the Community Shield against Mourinho's Chelsea on August 2.

"Life doesn't always turn out the way you think it will," Cech said, in an open letter yesterday to the Chelsea fans. "I thought this would never happen but it is time for me to say goodbye to Chelsea. The club in which I thought I'd hang my gloves and boots one day and finish my career."

In 11 successful years at Chelsea, Cech was part of 13 trophy-winning teams but fell behind Belgium goalkeeper Thibaut Courtois in Mourinho's pecking order last summer.

"I know I am not at the stage of my career where I want to be on the bench," Cech said. "That's why I spoke to Mr Abramovich about me staying in the Premier League and I'd like to thank him from the bottom of my heart for his support."

Mourinho is now hopeful of signing Begovic although Stoke have rejected Chelsea's opening offer. They are holding out for more than £8 million and are also interested in taking a player on loan next season. Chelsea still hope to complete a deal in the next 48 hours but they must also reassure Begovic, who would clearly find himself in Cech's position of understudy to Courtois.

Begovic could double his wages at Chelsea - and should also get chances to play in the domestic cups - but may want to see if Manchester United want to make him their replacement if David de Gea joins Real Madrid. Cech's arrival will also have big ramifications for Arsenal.

Wojciech Szczesny has made it clear that he wants to stay and posted a message on Instagram yesterday that welcomed Cech's -signing. "Delighted to have a chance to learn from one of the best goalkeepers in the world," he wrote.

The Colombia goalkeeper David Ospina is likely to feel rather less enthusiastic. Ospina had replaced Szczesny as Arsenal's No.1 goalkeeper last season and is expected to join Fenerbahce.

The Chelsea goalkeeping coach, Christophe Lollichon, may now follow Cech to Arsenal. Cech was also wanted by Paris St-Germain and, although he said it had been his "hardest" decision, became convinced by Arsenal after speaking to Wenger.

Cech said: "I hope that I can bring something a little extra to the team that can help. I had a good chat with him and it was the first time after the club approached me that I could speak to him in private for such a long time. He made me believe that this was the right step and that this is the club with a lot of ambition."

Wenger added: "Petr Cech is a player that I have admired for a long time. He has proven over many seasons that he is one of the outstanding keepers in the world and he will add great strength to our squad."

Arsenal have ended their interest in Chile international Arturo Vidal and, having not followed up an inquiry for Morgan Schneiderlin with a bid, appear content for the France international to join Manchester United. A holding midfield player had been Wenger's transfer priority in January and there were discussions then with Southampton about Schneiderlin but an asking price of £25 million, coupled with the form of his existing midfielders, prompted a rethink. Wenger is still assessing the market.

The Telegraph, London