Mikael Silvestre said he was as surprised as anyone about becoming the first player in 34 years to be sold from Manchester United to Arsenal.
"I still have the fire," Silvestre said after signing a two-year deal with the Gunners.
"I was looking for a new challenge and when Arsenal came in for me, I couldn't refuse. It was a very good surprise. I'm very happy to be here."
Silvestre's move shocked most observers because United manager Alex Ferguson has traditionally refused to sell players to teams he considers domestic rivals.
Last year, United refused to allow Gabriel Heinze to join Liverpool, instead selling him to Real Madrid.
Yet the move had Ferguson's blessing, according to Silvestre.
"I have a very good relationship with him," Silvestre said.
"That's why I stayed at Manchester for so long. Playing for him has been a great honour. He listened to me and didn't want to act against my wishes. It was difficult to leave, because I'm leaving some very good guys behind me."
Still, Silvestre said he was fed up with being on the bench, after making just five appearances for United last season.
He was contemplating what could have been an even more acrimonious move to Manchester City before being persuaded by Arsenal manager Arsene Wenger to move to London.
Arsenal needed to bolster their defensive line after Justin Hoyte's departure to Middlesbrough, Kolo Toure's recovery from malaria and Phillipe Senderos' thigh injury.
"We have a strong squad but a young squad and Mikael's versatility, experience and caliber will provide the extra depth we need to reinforce our challenge for honours this season," Wenger said.
The last player to leave United for Arsenal was Brian Kidd in 1974, when neither club was a major force in English football.
Since then, the teams have developed into bitter rivals and transfers between the two sides were virtually unheard of.
When Frank Stapleton left Arsenal for United in 1981 for 900,000 pounds it was seen as an act of betrayal by Arsenal supporters.
Viv Anderson is the only player to make the switch since then, joining United from Arsenal in 1987.
United's reserve goalkeeper Jim Leighton did join the Gunners on loan in 1991, although he never played for the first team.
