Celtic have signed winger Jonny Hayes from Aberdeen on a three-year deal for an undisclosed fee.
The 29-year-old Republic of Ireland winger scored against Celtic in the 2-1 Scottish Cup final defeat last season.
Hayes, who was under contract at Pittodrie until 2019, had also been linked with English Championship outfit Cardiff City.
Celtic attacking midfielder Ryan Christie, 22, will spend season 2017-18 on loan at Aberdeen.
Christie, who joined Celtic from Inverness Caledonian Thistle in 2015, was loaned to the Dons for the second half of last season and scored seven goals.
Former Leicester City player Hayes previously worked with Celtic manager Brendan Rodgers at Reading.
Aberdeen rejected two offers from Cardiff for Hayes in January, and the Championship side resumed their interest at the end of the season.
Cardiff manager Neil Warnock admitted defeat in their pursuit of the winger, though, with the player opting to rejoin Rodgers at Celtic Park.
Hayes made 206 Aberdeen appearances in all competitions, scoring 29 goals, since arriving from Inverness Caledonian Thistle in 2012.
He provided 19 assists in the Premiership last season, the highest in the division, and was a member of the Republic of Ireland squad called up for the 1-1 draw with Austria last week, although Hayes did not add to his three international caps.
“This is a huge honour for me,” Hayes told the Celtic website. “It was hard last year seeing all the celebrations and all the stuff on social media and you want that for yourself and to be part of it.
“You can’t get away from the Champions League. I can imagine it is the reason many players have wanted to come here.
“Whether you’re a football fan or not, everybody knows about the atmosphere of Champions League nights at Celtic Park. I’d be lying if I said I didn’t want a part of that.”