Briton Callum Smith’s bid to become a two-weight world champion ended in heartbreak after a seventh-round stoppage defeat by the terrific Artur Beterbiev in Quebec.

The Russian systematically broke Smith down to defend his WBC, IBF and WBO light-heavyweight titles.

He floored the challenger twice in the seventh before 33-year-old Smith’s corner pulled him from the contest.

“I think it’s because of luck,” Beterbiev, 38, modestly said.

He maintained his 100% record, having stopped all 20 professional opponents within the distance and is now targeting a unification fight against fellow Russian and WBA champion Dmitry Bivol.

“I need a fourth belt. It would mean in this category I have done my work,” said Beterbiev, who hopes to become the first undisputed light-heavyweight champion in the four-belt era.

Smith, the former super-middleweight champion, was stopped for the first time in his professional career, suffering a second defeat in 31 outings.

The former super-middleweight world champion, who turned pro 10 years ago, suggested he could retire.

“I’ve always wanted to the best. I’ve always believed I was the best and now it’s hard to accept I’m not,” Smith told Sky Sports.

“I’ve got an amazing family at home. I give a lot to boxing. Win or lose, I didn’t want to stay in boxing for a long time.”