Motherwell have confirmed that Australian striker Scott McDonald will join Celtic in the summer.
The deal is subject to the 23-year-old passing a medical and should be signed within the next few days.
Motherwell manager Maurice Malpas said: "It is well known that Scott wants to move on from Fir Park.
"The club has succeeded in securing a healthy transfer fee for him and ensuring that he will remain with us to the end of the season."
McDonald was disappointed to miss out on a January move to Rangers, who offered £400,000 on transfer deadline day.
But Rangers were reportedly unwilling to match Celtic's bid, believed to be £700,000.
McDonald has hit 12 goals in 34 appearances for Motherwell this season, including one against Celtic in October.
He will be best known to Celtic fans, however, for the late double he struck against them on the final day of the 2004-05 season which handed the SPL title to Rangers.
McDonald told the Fir Park club's website: "I have thoroughly enjoyed playing for Motherwell and I will leave with a lot of good memories.
"I hope the fans appreciate that I want to move on and develop my career and I would like to thank them for the support they have given me."
The player's agent said that Australia team-mate, former Celtic striker Mark Viduka, helped persuade McDonald to join the club he supported as a boy.
Lou Sticca told The Sun: "Mark Viduka has been in the international camp with Scott for the Socceroos.
"When he told him it could be Celtic or Rangers, there was only one team Mark was pushing for.
"Scott didn't need pushed to Celtic, but Mark was a convincing advocate of what he could achieve if he chose Parkhead."
The departure of McDonald could lead to a player exodus from Motherwell, with midfielder Brian Kerr warning earlier this month that he could be the first to follow.
He had said that they could not afford to lose McDonald if they wanted to improve their standing in the Scottish Premier League.