New Chelsea signing Shaun Wright-Phillips says he left Manchester City to improve himself as a player and to win honours.
Wright-Phillips completed his £21m transfer on Monday and said he hopes City fans "understand".
He said: "I want to be a better player and Chelsea is the club to do it with.
"I moved to Chelsea to win medals and challenge for awards. This is an opportunity of a lifetime - to have not come would be a mistake in my career."
The England international gave City boss Stuart Pearce assurances he would not leave City just before switching to Stamford Bridge.
But he admitted that, in the end, he could not resist the lure of the Premiership champions.
He added: "It was upsetting. But Stuart Pearce was a player and he understands the way football is.
"I'm sure he, and most players, would have done the same and taken the chance."
Blues boss Jose Mourinho is confident the England international will flourish at Stamford Bridge but offered no assurances about him holding down a first-team spot.
Wright-Phillips will be vying for one of the two wide roles with Damien Duff, Arjen Robben and Joe Cole but Mourinho said he would not be having too many sleepless nights about who to leave out: "It's not my problem. It's their problem.," he said.
"Shaun was involved with a good team and good players but Chelsea are a better team with better players and his conditions to improve are better.
"As a player he is too young to stay at this level. I will be sad in a few years if he is not a better player."
And Mourinho was convinced Wright-Phillips will soon adapt to Chelsea's style of play - which often sees one lone striker and two wide players who are also expected to fulfil their defensive duties.
Mourinho added: "I like to give freedom but there are certain principles of our play that you cannot lose but he is a very intelligent boy.
"If you have a players like Shaun you must use his potential. He can be a more a pure winger than our other players but at the same time he can also play from inside. He can play on the right the left or the centre."