British heavyweight Daniel Dubois knocked out Ghana's Richard Lartey in the fourth round at Wembley Arena to extend his unbeaten record.After trading heavy blows in the previous round, Dubois dropped Lartey with a superb right hand and referee Bob Williams called off the fight.Lartey arrived in London two days before the fight due to visa issues.Dubois, 21, has won all 11 of his fights, with 10 knockout victories."It was a firefight, and I was still basically trying to hit him with shots," he told BT Sport."I let my mind go then I thought, 'You know what, I need to pick the right shots'."I hit him with a good shot and caught him on the point where I wanted to all night, so it was a lesson learnt."The British Boxing Board of Control said on Wednesday that Dubois has agreed a deal for a British title fight with Joe Joyce, who was ringside in London on Saturday.Joyce's next fight will be on the undercard of Billy Joe Saunders' match against Shefat Isufi in Stevenage on 18 May after signing with Frank Warren, who also promotes Dubois.When asked if he will beat 33-year-old Joyce, Dubois said: "Definitely - as long as the preparation is right, I stay focused, listen to the people around me, I'll beat anyone I believe."Joyce, who has won all eight of his bouts, said he thought Dubois "got a little troubled" by Lartey."It was a very entertaining fight, he got the job done," said Joyce."Fighting him is an option - I've got a fight in Stevenage, that's a good warm-up, then I should be out again in July