Mannio opened 2009 with a massive personal best of 85.70, an improvement of more than four metres on his previous best. This mark was only beaten that year by five throwers worldwide and would remain his season best, even though he also exceeded his 2008 best in all of his next four competitions and either exceeded or equalled it in a total of ten competitions over the year. He also finally struck international gold: again entering the European U23 Championships as the leading favorite, he was passed in the last round by Czech Republic's Petr Frydrych but rebounded with a championship record of 84.57.