Former promoter Panos Eliades is one who believes Lewis has cut it fine in terms of acclimatising to 6,000ft.

Scientists suggest either six weeks or 48 hours on site are the best long and short term periods to adjust to thinner air.

Eliades, who handled Lewis’ career for 10 years until their recent split, observed: ‘‘I do feel he’s gone in late. I think he’ll either knock out Rahman early, or he’ll struggle.

‘‘Going there that late, he may struggle with his breathing, if it’s jabbing and moving, another David Tua fight.

‘‘I think he’s always had a problem with his breathing. We might find it a lengthy fight and he may not be able to knock out Rahman. It depends how well Rahman takes a punch, it could go two rounds or it could be a horrible fight.’’

Indeed, Lewis was examined by medical officers on his arrival in Johannesburg and the effects of making the long journey by private jet from Nevada were very much in evidence.

Lewis believes he has trained and fought enough at altitude for it not to be a problem, though the champion has tired before in long fights, notably against Zeljko Mavrovic in sea-level Connecticut in 1998.

But Lewis is now on such a roll that his self-belief is soaring.

Since Mavrovic, he won his series against Evander Holyfield to become undisputed champion, blew away Michael Grant and Frans Botha, and never gave the dangerous David Tua a look-in last November, boxing his way to a lop-sided verdict.

One of Rahman’s two defeats was at the heavy hands of Tua. He was leading on all three judges’ cards when he was hit after the bell at the end of the ninth.

Rahman was given no extra time to recover from the late blow and was stopped in the 10th.

‘‘You could say Rahman got unlucky against David Tua. I’m giving him another opportunity to prove himself, small opportunity because he’s not going to get anywhere because I’m going to knock him out,’’ said Lewis.

‘‘Hasim’s trying to steal my thunder, but I’m coming with my thunder and lightning. It’s going to be a different story. I’m way ahead of schedule with my training.

‘‘Rahman’s never seen a boxer like me. In four or five rounds he’s getting knocked out.

‘‘My preparation’s been really good, I’ve got to thank Emanuel Steward, he’s a great trainer, a trainer of champions. He knows exactly what I need, certain areas where I need to be sharpened up.’’

‘Rock’ Rahman was 20 before he pulled on a pair of boxing gloves, and did not get paid for fighting until 25. He comes from a middle class family in Baltimore, and his brother studied to become a surgeon.

‘‘I don’t expect him to give it to me,’’ said Rahman.

‘‘And I’m not waiting for the judges to give it to me. I’m going to take that title, it’s as simple as that. I don’t believe any of the guys can punch like I can.

‘‘I’ve been bench-pressing 450lbs. I’ve added more punching power and muscle. It’s definitely time. Lewis can’t keep beating up these young guys over and over again because they are turning into old guys. You just can’t keep winning.’’

Clearly, Rahman has not come just to keep the seat warm for a mega-million Lewis v Mike Tyson showdown.

And Lewis insists he is simply keeping focused on the ‘Rock’.

‘‘I’ve got a lot of notches on my belt, I would love a Tyson notch,’’ said Lewis.

‘‘This era is my era, it would be disappointing for not only me but the public if they weren’t able to see that fight.’’