At this early stage of a Lions tour there is no such thing as a team of midweek "dirt-trackers". Tonight's side to face their locally based namesakes, in fact, is not a million miles away from the potential Test XV on Saturday fortnight, with only Lee Byrne, Paul O'Connell and, perhaps, Stephen Ferris absent from Ian McGeechan's possible first-choice line‑up. Little wonder that Shaun Edwards believes this is the moment for the visitors "to put down a marker".

Edwards, more than most, is keenly aware that another below-par performance will leave the Lions as exposed as a limping antelope in a big-game reserve. Next up are the Cheetahs in Bloemfontein on Saturday followed by the Sharks and Western Province within four days of each other. The honeymoon period is already over and another faltering effort will make it harder still to generate the momentum every successful tour needs.

There is an urgent need, in short, for someone to step up and provide what Rob Howley described as "that X-factor" to banish the "despondency" which followed the opening game against the Royal XV. Twelve years ago, in this corresponding fixture, it arrived in the form of a wonderful solo try by John Bentley which convinced the entire tour party that something special might be brewing in the Tests. If Brian O'Driscoll, Ugo Monye or Rob Kearney are able to weave similar magic the subsequent lift to collective confidence will be equally inestimable.

Defence will also be crucial, as it always is whenever Edwards is involved. "Pear‑shaped" was his verdict on last ­Saturday's first half and the mitigating factors – heat, altitude, rustiness and an unusually narrow pitch – will no longer be admissable as excuses at Ellis Park. "We need to be on the money because you're not going to win a series if you let in three tries against the Springboks," cautioned Edwards. "I'd like to think the ­players will have more energy and zest than last weekend. We want to put a marker down and play for 80 minutes."

Edwards's competitive instincts have been further stirred by the reaction of most locals when they discover he is the Lions' defence coach. "A few of them wish me good luck and say I might need it. It adds a little bit more motivation. The players out on the pitch are an extension of me. If they miss a tackle or make an error I'm out there with them, not in body but in spirit." The players also know better than to disappoint the former rugby league legend. "If you miss a tackle or you're out of position you know you're going to get a rollicking," sighed Mike Phillips, the Wales scrum-half whose joust with the lively Jano Vermaak will be among this evening's key contests. "Defence is going to win us the game."

The Lions should also keep an eye on the Emerging Springbok full-back Louis Ludik while Edwards compares Willem Alberts, the home side's No8, to the distinguished former Lion Scott Quinnell. McGeechan's men, even so, will be deeply disappointed if they continue to turn over the ball with the same costly regularity against a forward pack featuring Brad Mockford, a lock who has latterly been turning out for Newbury. Phil Vickery, for one, believes his side are in the mood to make a forceful statement.

"It's certainly going to be a step up. I've felt a real difference this week, a real seriousness about what lies ahead," he said. "The good thing for the game against the Golden Lions is that we have Saturday's match to analyse. It is potentially the biggest match of their lives and they are sure to raise their game. We are under no illusions about the test that lies ahead."

The squad, who were joined yesterday by Leigh Halfpenny, have already grown accustomed to frequent drug-testing, with 10 random players having supplied on-the-spot samples this week. Tonight's task is to roll up their sleeves on the field and give the 2009 tour a shot in the arm.