Kevin Mitchell no longer resembles a boxer in decline.

At various stages in the past two years, the 27-year-old has looked heavy-set and mournfully detached from the promise of his career. An accumulation of troubles in his life had altered his priorities. Now they have been discarded and he looks, at least, to have recovered a lean, menacing appearance.

Mitchell is stalked by the years of disillusionment, though, when alcohol was a distorting influence. Nobody can be certain that his technical aplomb and explosive power did not suffer some damage, although Mitchell is adamant he retains his old expertise.

Ricky Burns will uncover the true extent of Mitchell's rejuvenation when he defends his WBO lightweight title against the Englishman at Glasgow's SECC tonight. They are contrasting figures. Burns, for instance, tends to celebrate his world title victories with a few days off before returning straight back to training. He is practically teetotal, and the simplicity of his life is a cherished quality. Physical conditioning is part of his everyday routine, and his fight preparations tend to be exercises in honing his weight rather than reducing it.

The Scot has been steadily progressing, winning first the WBO super-featherweight title, then the lightweight championship. Each world-class opponent that was overcome could be seen as a direct riposte to the doubts about his ability. Burns is an accomplished boxer, even though there are no flourishes to his talent.

He does not possess a thunderous punch, and only nine of his 34 victories have come by knock-out. Yet the lack of flamboyance is in itself an expression of superiority. Burns might as well be disdainful of showmanship, since his triumphs are the result of his all-round capability, diligence, and the shrewd tutelage of his trainer, Billy Nelson.

The 29-year-old is relentlessly disciplined, and that allows him to undermine the best of his opponents. Versatility is also an advantage, since it allows Burns to live by his wits in the ring. He has earned his place among the elite through the clear-minded application of all of his attributes.

"Whatever happens, Ricky will adapt to it," Nelson said. "Kevin's up there with the best of [Burns' previous opponents], but I do firmly believe have the better fighter. [Mitchell] has a knockout punch, but against who? No world-class opponents. He's fought maybe two guys who are borderline world class, and he lost to [Michael] Katsidis, although he has made excuses for that."

Mitchell's defeat to the Australian two years ago is his only loss in 34 fights. He had only recently separated from the mother of his two children and his life was in such disarray that the nights leading up to the contest were spent out late drinking and cavorting.

He has restored some calm to his existence, and sees his boys four days a week. Bill Ives, a multi-millionaire who made his fortune from the steel industry, has become a mentor, providing a source of reassurance and authority.

At yesterday's weigh-in, Mitchell hugged Ives tenderly, and planted a brief kiss on his cheek. The challenger stripped naked to step on the scales, but was one ounce under the 135lb limit. Burns was exactly on it. There were none of the usual histrionics, since Burns and Mitchell are friends from their days as amateur fighters. When they stood face to face for the cameras, there was no obvious tension, even if Mitchell yelled fiercely once they had separated.

Burns engagingly lacks conceit, but nobody would mistake him for a patsy. He will be scrupulous in the way he attempts to dismantle Mitchell. The Londoner should be in his prime, but he is still in a period of recovery. He still carries the potential to unleash a decisive punch, but Burns is capable of managing that threat.

Most in the boxing game are genuinely split in their assessment, since the fight is so close to call. It may come down, in the end, to heart. "Mitchell is one of those kids you get the best out of in adversity," said Frank Warren, the promoter. "He has a great left hook. If any punch can do it against Ricky, it is a left hook. But Ricky is the most improved fighter in the UK, and I don't think he has had the recognition he deserves. When it comes down to it, both of these guys will wind up in the trenches."

Burns might be more comfortable there, since there have been no physical setbacks to overcome. The champion should, then, do enough to retain his belt.