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The current Aberdeen captain who's also played for the likes of Hearts and Celtic says he's quitting despite having a year left to run on his contract.
The 34 year old has taken the decision because he thinks body is no longer capable of playing at the highest level.
Hartley has not played in recent weeks because of a knee injury - and his 27-minute appearance in a 2-1 win over St Mirren on March 16 will prove to be his final match in a career that also saw him play for Hamilton, Raith Rovers, Millwall, Hibs, St Johnstone, Hearts and Bristol City.
A statement on the Aberdeen website said: "Everyone at Pittodrie would like to thank Paul for his contribution over the past season, which has been excellent, and we wish him all the very best for the future."
After the Cup win over the Buddies, Dons manager Craig Brown had hoped to be able to call on Hartley's services for the semi-final with Celtic, but the player broke down and this is what appears to have confirmed his decision to retire, something he was considering before the injury.
Hartley picked up the last of his 25 caps in Craig Levein's first international - a friendly win over the Czech Republic, though he would later be selected for the squad that faced Lithuania and Lichtenstein at the start of the current Euro 2012 qualifying campaign.