Celtic have confirmed the signing of midfielder Scott Allan on a four-year deal from Hibernian.
Allan, a boyhood fan of Celtic's Old Firm rivals Rangers, underwent a medical on Friday ahead of his move to the Scottish champions.
Rangers had, in fact, failed with three bids for Allan, but the 23-year-old former West Brom player will now turn out for Ronny Deila's side in the Ladbrokes Premiership.
He said: "I am absolutely delighted to sign for Celtic, such a fantastic club.
"It is such an honour to be given this opportunity and I can't wait to get started and play my part in bringing success to Celtic and our supporters.
"There are so many exciting challenges ahead for us now in Scotland and in Europe and I am looking forward to being part of all that lies ahead.
"I know a number of players well at the club already, so it will be great to team up with these lads again as well as all my other new team-mates, and I know we will work hard together to bring more good times to our fans.
"I know the high-quality of players at the club and I know it will be a big personal challenge for me but it's one I'm ready for and one I am relishing.
"I would like to thank the many fans who have already welcomed me to the club. I really appreciate this support."
Celtic manager Ronny Deila said: "We're really pleased to welcome Scott to Celtic.
"He's a player of huge potential and someone who is hungry for success, a young player who can have a big future at our club."
Meanwhile, James Forrest believes Celtic fans will readily forgive Allan's Rangers allegiances.
Celtic's Old Firm foes Rangers have failed with three bids for Allan, a boyhood fan of the Ibrox club, and Hibernian were adamant they would not sell the player to their Championship rivals.
Forrest, a former Scotland Under-21 team-mate of Allan, is sure the former West Brom player will have no problem in being accepted by Celtic supporters.
"Once you start playing games then everything gets forgotten about," Forrest said.
"I am sure the fans will be right behind him because he will be a really good player for Celtic.
"He is a type of player Celtic look for and he will fit in well.
"A massive club like Celtic are always looking to bring in players of top quality and I am sure that Scotty can come here and do really well."
Forrest rejected the notion that Celtic moved for Allan only to get one over on Rangers.
The Scotland wide-man, speaking at the Hoops' Lennoxtown training ground ahead of the visit of Inverness today, said: "I don't think it has anything to do with that. Celtic are always looking to bring in top players and if we do sign him he will be looking to play and do well, and that's what we want, competition for places."
Deila is confident that skipper Scott Brown, who has missed the last two games with a hamstring injury, will be back for the first leg of the Champions League play-off against Swedish side Malmo at Celtic Park next Wednesday night, which follows the visit of Inverness today.
The former Stromsgodset boss, however, believes the loss of the Scotland captain is not as detrimental to his team as it would have been last season.
He said: "Scott was stiff in his hamstring after the Qarabag game. He is moving forward all the time and is going to do everything he can to get ready, maybe for Saturday, and hopefully Wednesday."