They will do well to be cautious for the Lions' forwards have been put through a shuddering experience by Nigel Horton and his travelling Richter scrummaging machine.
The Lions' management were never in doubt that the key to success in the three-Test series against South Africa would be to hold their own in what promises to be a ferocious clash between the opposing front rows. And, if there was any question as to the validity of that prognosis, it was surely put to rights in the first three matches of the tour when the Lions' forwards were given the sledgehammer treatment by provincial teams.
But help was at hand, just as it had been in the week the tourists spent in England prior to departure for South Africa. As part of of the mutual determination of the manager, Fran Cotton, and the coach, Ian McGeechan, to see that the players wanted for nothing in the way of specialist advice and assistance on the Lions' first professional tour, they enlisted the support of Horton and his strength-sapping, two tonne machine that gives the pack their power.
It is no ordinary device, any more than in his day, Horton was a run- of-the-mill forward while at Moseley.
Horton, capped 20 times for England, with hands like hams and a beguiling try-me-if-you-dare smile, was a brilliant line-out jumper and a superb scrummager who has used his playing experience and the engineering skills of Paul Richter to build a heavyweight monster which stretches every forward to the limit, and can fight back if all eight look as if they are getting the better of it.
Six weeks before the tour began, Horton shipped four tonnes of equipment out to Durban, hired an eight-tonne truck and a six-metre trailer and, along with Irishman Des Beirne, planned a 4,000-mile road journey around South Africa to fit in with the Lions' schedule. Thus far, it has been a voyage of discovery as the Lions' pack have continued to improve.
"Measurement is so important," Horton said. "You must have feedback. By working on compressed air, the Richter converts everything into kilos. Not only can it quantify the shove of the whole scrum, it can identify a shortfall in an individual player's performance."
Cotton has no misgivings about the machine's effectiveness: "We had to come to terms with much stronger than anticipated South African scrummaging and it has been a great help in the way the forwards have adapted."
After a 50-scrum training session, Jason Leonard, dripping in perspiration, declared it the nearest thing to live scrummaging: "Nothing will simulate a real scrum. But this tells us what pressure is coming back. It has improved our cohesiveness; and we are much more solid as a unit."
The Lions will certainly need to be much more resolute scrummagers against the Boks than they were in the early tour games or disaster beckons. After the Western Province match, Garry Pagel, their destructive loose- head prop, declared that the Lions' front row were "soft." That hurt the Lions more than any other criticism from opponents or media so far during their stay in South Africa.
If the Lions' forwards can make the Springboks squeal in the tight here on Saturday, Nigel Horton will be humming a happy tune throughout the 1,050-mile trek back to Durban. But he will still be ready to inflict more pain on his charges, on an unimaginable scale.