Belfast Giants are "shocked" after coach Doug Christiansen left the Odyssey team to take charge of the Sheffield Steelers.
Christiansen spent three years with the Giants and led them to the Elite League title in 2012.
The Giants finished second in both the league and play-offs this year.
"I had three three fantastic years in Belfast but right now in my career this was an opportunity I couldn't pass up," said Christiansen on Tuesday.
He added: "I want to be somewhere that I can win trophies and work with a good budget and this is the place for me.
"I'm going to bring in outstanding players, who are great people, great in the community and importantly great team-mates."
Former Giants coach Steve Thornton is an early contender to replace Christiansen at the Odyssey.
"The Giants were only informed after 18:30 BST on Monday by Doug Christiansen and have been left shocked by the timing of this," the club said.
While unhappy with the timing of his decision, the Giants added that they "would like to thank Doug Christiansen for his 100% work ethic and commitment to the Giants during his three years behind the bench for the Belfast."
Christiansen's departure came less than 24 hours after he was behind the bench in the play-offs final, losing to Nottingham Panthers in overtime.
The Panthers also pipped the Giants to the Elite League title although Belfast won the inaugural Earhardt Conference Trophy.
The 34-year-old American has been appointed Steelers coach for the next two seasons.
Christiansen replaces Ryan Finnerty, who left Sheffield last week after his contract was not renewed.
"I am sure this is the appointment that will help see an upturn in the club's results and title aspirations," said Steelers owner Tony Smith.
"Our fans deserve the best we can find and a man who has strong leadership qualities, technical ability and motivation powers to get the best out of our team every single night.
"I'm delighted that the move has come about so quickly, that was unexpected as I thought finding the right candidate for the job would take a little longer.
"However, after speaking with Doug I was sure we had the right man right in front of us."