Manchester United have finalised the signing of Celtic midfielder Liam Miller on a pre-contract agreement.
The 22-year-old has put pen to paper on a deal which will see him move to Old Trafford on 1 July.
Miller, who turned down a contract worth £1m a year at Celtic, said: "As a young boy I only supported two clubs, Glasgow Celtic and Manchester United.
"I am honoured to have played for Celtic for six years and now I look forward to joining Manchester United."
Miller added: "It's very exciting and is going to be a challenge to play for one of the biggest clubs in the world."
United manager Sir Alex Ferguson said: "We recognised the potential of Liam, he has had a great season at Celtic. He is very much part of our progressive thinking of developing a young team over the next few years."
Old Trafford chief executive David Gill added: "I am pleased to have Liam joining
us, it focuses our continued commitment to bring in young players for the future."
Miller's progress at Celtic Park had been hampered by injury problems earlier in his career and he was farmed out to Danish club Aarhus for a season in 2001.
But the Cork-born midfielder broke into the Celtic first-team this season and impressed both domestically and in the Champions League, although he was left on the bench against Rangers at the weekend.
News of Miller's departure comes 24 hours after Celtic's capture of Scotland midfielder Stephen Pearson from Motherwell, who was also out of contract in the summer, for a cut-price £350,000.
Miller first attracted the attention of Celtic when playing for his local side in Ovens, County Cork, and moved in Scotland in 1997.
He has been a regular in the Ireland Under-21 side and was called up to the full squad for the friendly against Canada in November.
Miller would follow in the footsteps of Brian McClair, Lou Macari and Paddy Crerand in moving from Celtic Park to Old Trafford.