Audley Harrison got his latest heavyweight comeback under way in Las Vegas on Saturday night when he laboured to an unconvincing fifth round win over American journeyman Jason Barnett.

In his first fight since his crushing third round knockout defeat to Michael Sprott in February last year, former Olympic champion Harrison looked cautious but made his weight advantage of over two stones count.

The contest was waved off after one minute and 48 seconds of the round when Harrison clattered Barnett to the body with a right hand and Barnett was not allowed to continue despite clambering to his feet.

It was little surprise Harrison looked sluggish as he engaged in his first fight in 14 months following problems in and out of the ring, including the death of his brother and a serious car crash.

But judged in the context of his continued boasts about future domination of his division, the British fans were entitled to expect more against an opponent with a modest 10-6 record.

Harrison threw out some good right hands in a slow first round and landed at will from the second onwards, finishing the third with a flourish before switching downstairs to finish the job.

Harrison said: "I felt a little rusty. It's been 18 months since I've been in the ring but I'm happy with my jab, that's what I've been working on and I got the rhythm.

"When my corner told me to start going downstairs that's when I broke him down. He was a live opponent and after 18 months I'm just happy to be back."