Billy Joe Saunders returned to the ring after a year of inactivity by forcing Charles Adamu to retire after four rounds at Manchester Arena.
Saunders, 29, could not defend his WBO world middleweight title in October after returning an adverse drug test, prompting him to vacate the title.
He returned to pummel Adamu, 41, with the Ghanaian withdrawn by his corner after 12 minutes of the bout.
Elsewhere, Nathan Gorman beat Razvan Cojanu and Tommy Fury won on debut.
Saunders moved to 27 career wins without defeat and will look to rebuild after a frustrating year, where his team claims the use of a “common decongestant nasal spray” led to a failed doping test.
The Briton was not allowed to defend his title in the US due to a reading returned in a Voluntary Anti-Doping Association (Vada) test.
But he would not have failed a test in the UK as the substance in question – oxilofrine – is not banned during an out-of-competition period by UK Anti-Doping.
Fury, brother of former world heavyweight champion Tyson, won 40-36 on the referee’s card after a four-round contest against Latvian Jevgenijs Andrejevs, 37.
The 19-year-old boxed smartly, landing a solid right uppercut in the first round as he repeatedly stalked an opponent, who now has 103 defeats from 116 bouts.
Fury said: “I’m learning. If it wasn’t for the excessive holding I would have got him out of there.
“Fight by fight I’ll get better. Tonight was the start of my journey. I want to be an undisputed world champion. I know it sounds stupid but I wouldn’t be in the game otherwise. I’m in no rush but I’ll get there.”
Heavyweight Gorman, who trains under former two-weight world champion Ricky Hatton alongside Fury, dominated Cojanu and cleverly negotiated a height and reach disadvantage.
Romania’s Cojanu – who challenged for a world title in 2017 – took a heavy uppercut in the fifth round and the same shot was driven through his guard in the 10th, as Gorman built on a solid early pace to win 119-109 119-109 120-108 on the cards.
“Good win against a big, solid heavyweight,” tweeted Gorman. “Great rounds under my belt.”
Gorman, 22, now has 15 wins from 15 outings and could be moved towards a meeting with fellow Briton Daniel Dubois in 2019.