Olympic silver-medallist Stevenson improved to 22-0 with 10 wins inside the distance, making his first defence of the title he won with a narrow decision over Dominican puncher Edwin De Los Santos last November.

That made Stevenson a three-weight world champion, but it was a lacklustre showing from both fighters and Stevenson did little on Saturday to quiet critics demanding more fireworks in his last fight under contract to promoter Top Rank.

After a slow start that left fans at the Prudential Center in Stevenson's home town restless, Stevenson began to wear down Olympian Harutyunyan with a series of body shots in the sixth round. He maintained a measured pace through the 12th, the judges scoring it for the champion 119-109, 118-110 and 116-112. Harutyunyan, in his first world title bid, fell to 12-2 with seven wins inside the distance.

At the end of the fight there were some boos from the crowd but Stevenson defended his performance, saying "It's kind of hard to prove it if you don't got a fighter trying to fight back”. Stevenson has drawn criticism for a cautious and defensive style in the past. Speaking to ESPN he added, "I want to fight the best fighters.

"That's how you're going to get to see the best version of me, when you put me in the ring with somebody else that wants to fight back and compete."

On the same card, Brazilian Robson Conceicao dethroned WBC super featherweight world champion O'Shaquie Foster with a controversial 12-round split decision victory. Foster's jaw dropped in stunned consternation as the scores were read out after a fight in which he, and many onlookers, felt he had done enough against an opponent who didn't appear to land any damaging blows.

Though two judges saw the bout for Conceicao 116-112 and 115-113, while the third scored it 116-112 for Foster. "I do think I was actually the winner," said Conceicao, a 2016 Olympic gold medallist, who improved to 19-2 with one drawn and nine knockouts.

"I tried way more. He didn't come to fight, he was actually running, running, running, I kept on striking, so I was the winner." Foster fell to 22-3 with 12 knockouts. "I thought it was a shut-out," Foster said. "I didn't get touched but with a head-butt. I don't know, man ... I want a rematch."