Brian Smith: Opponents panic every time George North gets the ball - he just has to be Test fit

Halfway through the tour, the Lions are concerned about their injuries. Not, ironically enough, the serious injuries - Cian Healy's ankle, Tommy Bowe's hand - but the relatively minor, deeply frustrating ones: the hamstring pulls and shoulder bumps, problems that players tend to pick up when the rugby is a little easier than anticipated.

As a coach you often find yourself worrying in pre-season, when things get fast and loose in the warm-up fixtures and players find themselves doing a lot of running at high speed. The Lions are facing this kind of situation in Australia. The moment I tuned in to their game against the Combined Country XV, the “boys from the bush”, in Newcastle on Tuesday, I immediately thought: “Uh-oh, there are a lot of guys out there accumulating a lot of miles at a pace they're not really used to.” Conditioning these days is geared towards a tougher, more attritional, more physically demanding style of close-quarter rugby. When highly tuned professional athletes are suddenly placed in a different situation, issues can arise.

One of those issues is affecting the Welsh wing George North who, to my eyes, has been the standout Lion on the tour to date. If Warren Gatland and his coaching team are worried about this guy, I'm not surprised. He's one of the real game-changers in the party, one of the people who could easily make the difference in a tight series with the Wallabies.

For North to develop a hamstring injury now, a week out from the first Test, is seriously bad news, especially after the way he played when he came off the bench against Queensland Reds last weekend – and I'm talking as a proud Queenslander here. I would even go so far as to say that he's in John Kirwan territory, which is saying a hell of a lot. There haven't been many modern wings as effective as the All Black, who scored some famous tries at the first World Cup in 1987.

I remember playing a game for Queensland against Auckland at Eden Park in '85 when Kirwan broke from deep in his own half, ran over Brendan Moon (a bloody good defensive player), ran over Roger Gould (ditto) and surged all the way to our line. I was chasing him on the cover, thinking all the time how glad I was to be behind him rather than in front of him. I also remember thinking: “The way this guy's going, he could score at our end, turn round, run through us all over again and score another one at their end.” And then I'd be the one in the firing line, at risk of being knocked cold.

Right now, North looks as good as Kirwan looked then. Every time he lays hands on the ball, even in unpromising positions a long way from the opposition red zone, he has defences in a panic. He's big, he's quick and he knows how to hurt the opposition. If the Lions lose him for part of this Test series, no one will be happier than the Wallabies.

Talking of wings, a small digression: I'm delighted that Marland Yarde, with whom I work at London Irish, is winning his first full England cap in Argentina this weekend. Marland is a player with a big future in the game and he deserves this opportunity. I said early last season that he could answer a lot of questions for England in the No 11 position and that he'd be capped sooner rather than later. I don't want to say “told you so”, but…

Back with the Lions, they can at least expect to be tested by the New South Wales Waratahs today, because teams coached by Michael Cheika don't lie down. If Michael Foley's selection policy at Western Force ahead of the first game on Australian soil pretty much guaranteed a no-contest, Cheika is not the sort to run up the white flag. He may have been a burly No 8 back in the day, but he could play some footy. He likes his forwards to have plenty of dog, and his backs to have some razzle-dazzle about them.

So far, the Lions defence has not really been tested. The games in Perth and Newcastle were too easy, and while the Reds had the capacity to give the tourists a good working over, the Brisbane rain cramped their style. But the Waratahs are a clever side who like to give it a crack with ball in hand. Cheika and his fellow coach Alan Gaffney are men of the Randwick club, and Randwick are known as “the galloping greens” for a reason. Think back to the halcyon days of David Campese and you'll get the picture.

For a coach like Cheika, this is just about the perfect fixture: the chance to give it a real rip, without any great public expectation of victory. And I'm beginning to think that the Wallabies, hidden away up there on the Sunshine Coast in their self-contained training camp, are also in a good spot. Certainly, their coach, Robbie Deans, has a lot more control over his players' conditioning than Gatland has over his Lions.

We still don't know whether Deans is planning to fight fire with fire in the first Test by picking a big defender like Pat McCabe at inside centre or whether he'll take the second ballplayer option that has been productive for him in the past, but we do know this much: in Brisbane next weekend, the Lions will encounter a lot of stuff they haven't yet experienced.