كتب : Hatem Maher
Serbian midfielder Dejan Stankovic opened the scoring as early as the third minute when he robbed a defender inside the area and hit a low shot into the net with aplomb.
Skipper Javier Zanetti doubled their lead just past the half-hour mark, finishing off a back-heeled pass from striker Diego Milito.
Milito turned from provider to scorer in the 73rd minute as he notched home on the rebound after Seongnam keeper parried a Samuel Eto'o shot into his path.
Inter will be looking to ease pressure on beleaguered coach Rafael Benitez and win the title at the expense of Mazembe.
Mazembe, Champions League winners in 2009 and 2010, made history after becoming the first African team to reach the Club World Cup final following a 2-0 victory over Brazil's Internacional on Tuesday.