for UEFA Euro 2012 and was given the number 11 jersey. On 18 June 2012, he captained the Republic of Ireland on his 100th cap against Italy, their final group game of the tournament. This turned out to be the last match he played representing his country. He announced his retirement from international football on 24 August 2012. Coaching career During his last playing season at Shamrock Rovers, Duff coached the club's under-15 team. On 16 April 2016, it was announced that he would take on a coaching role with the Republic of Ireland under-15s, in line with the recommendation from FAI High Performance Director, Ruud Dokter, that more ex-internationals get involved in coaching roles with the national team setup. On 31 July 2016, Duff joined the Shamrock Rovers first-team coaching staff until the end of the season, with the intention that he would then take control of the under-15 group he previously managed, then competing in the League of Ireland U17 Division. Duff was appointed to a reserve team coaching position with Celtic in January 2019. When Neil Lennon became interim manager at Celtic in February 2019, Duff was promoted to first team coach, with John Kennedy promoted to assistant manager. After the club completed a third successive domestic treble, Lennon was made permanent manager, with Duff and Kennedy retaining their roles. Celtic secured a ninth league title in-a-row and fourth straight League Cup in 2019–20. On 5 April 2020, Duff was announced as the assistant manager of the Republic of Ireland senior team to Stephen Kenny, who replaced Mick McCarthy. On 24 June 2020 it was announced that in conjunction with his role as assistant manager of the Republic of Ireland senior team, Duff would also become head coach of the under 17 team at League of Ireland club Shelbourne. On 8 January 2021, Duff stepped down as Kenny's assistant. Shelbourne On 3 November 2021, Duff was appointed as the first team manager of League of Ireland Premier Division club, Shelbourne. His first match in senior management was a 3–0 loss at home to rivals St Patrick's Athletic on 18 February 2022. Personal life Duff was born in Ballyboden, County Dublin. Duff married Elaine in June 2010 at Babington House near Midsomer Norton in Somerset. The couple's first child, Woody, was born a year later in the county. Duff is also a rugby fan, and is personally acquainted