Edmondson, 29, was edged on decision (95-95, 96-94, 96-94) in a tight contest during the undercard for Oleksandr Usyk vs Daniel Dubois’ second fight.
Edmondson looked baffled when the scorecards were read out in favour of his Polish-born Ukrainian opponent, having felt he did enough to secure a career-progressing win.
After a slow start, Edmondson pinned Lapin into the corner at the end of the fourth round, and the 28 year old could only get out by holding onto ‘The Saint’.
In the eighth round, Edmondson forced Lapin back into the ropes, and the six-foot-six-inch southpaw got tangled twice.
Lapin responded with a combination of blows in the ninth round – his best of the night – which may have been the deciding factor in the eyes of the judges.
With this win, Lapin is now IBF Intercontinental, WBA Continental and WBO International light-heavyweight champion.
Edmonson’s record has dropped to 11-1 (3 KOs), but he should be proud despite suffering a tight defeat, which could have gone either way.