Mikel Arteta has insisted he did not let Everton down by pushing through a transfer request late on Wednesday's deadline day to seal a move to Arsenal.
Everton had rejected a £10m bid for the midfielder but once the Spaniard, 29, put in his request, manager David Moyes decided not to stand in his way.
The switch, which was completed close to the 2300 BST deadline, left Everton with little time to find a replacement.
Arteta said: "I've been as professional as I could but that is football."
The deal had looked dead after talks between the two clubs broke down but it was revived soon after Arteta handed in his transfer request an hour before the deadline.
Everton manager David Moyes quickly decided he did not want to keep an unsettled player who was not fully committed to the club.
Arteta said he hoped manner of his departure would not overshadow the six-and-a-half years he spent at Goodison Park.
"It is a big opportunity for me and my family and I think it is the right time for me to take it," he said.
"It is a big challenge, a different challenge, fresh for me and I want to see myself on the biggest stage, the Champions League.
"I am 29 years old so I haven't got much time left to take a chance like this one. I think I have done my best for Everton.
"I always try hard, I have been as professional as I could and I was grateful for the support and the love that the club and the fans showed me.
"It is very difficult to say goodbye. I still can't believe it but at the same time I think it is the right moment for everyone," he added on Everton TV.
"That is the way football is, there is always a start and an end and today is the end of probably the best time of my career. I am never going to forget it.
"Obviously I am never going to forget what I have done here and what the people and this club have done for me."
Arteta's departure coincided with striker Jermaine Beckford's move to Championship side Leicester, while the arrivals of Real Madrid midfielder Royston Drenthe and Argentine striker Denis Stracqualursi on season-long loan deals were Everton's only acquisitions in the transfer window.