on 23 september 2011, haapoja won his first major regional title by defeating faisal ibnel arrami via unanimous decision (ud) to become the european union cruiserweight champion. he made two successful defences against ian tims on 21 january 2012 (twelve-round unanimous decision) and francesco versaci on 15 september 2012 (fourth-round stoppage), but lost the title to mateusz masternak on 15 december 2012 (unanimous decision). consecutive losses came against silvio branco on 6 july 2013 (tenth-round technical decision) and rakhim chakhkiyev on 15 march 2014 (ninth-round tko), both times for the vacant wbc silver cruiserweight title.