Career
Haapoja made his professional debut on 8 April 2006, losing a four-round points decision to Remigijus Ziausys, who also debuted. He lost for a second time to Denis Bakhtov on 22 May 2008, which was for a WBC and PABA regional heavyweight title. A defence of this title against Jarno Rosberg, which went the ten-round distance, was later relegated to a no contest after Rosberg was caught for steroids.
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. On 31 January 2015, Haapoja suffered his sixth professional loss when he was stopped in two rounds by Serhiy Demchenko.
In a rematch on 23 May, the fight ended in a ten-round split draw.
