Shaun uses an umbrella to put wind up mighty Boks

visits a highly motivated Welsh camp ahead of the semi-final with

Dynamic duo: with defence coach Shaun Edwards
Vital component: Jonathan Davies is back, seen here fending off Jale Vatubua of Fiji Inset: Injury woe for Liam Williams
PICTURES: Dynamic duo: Warren Gatland with Getty Images
Big match attributes: Leigh Halfpenny was man of the series for the 2013

IF coaches alone were able to dictate the outcome of semi-finals you would put your money on the Welsh partnership of Warren Gatland and Shaun Edwards every time.

Their tactical cunning and motivational powers are two very good reasons not to write off as they face South Africa in Yokohama today.

Gatland and Edwards will love the script of a battered and bruised Wales side coming into the game as underdogs against the big bad Boks, who were every bit the schoolyard bully in their quarter-final against Japan.

Ever since they were together at , before the masterstroke WRU decision to sign them up over a decade ago, Gatland and Edwards have been the best ‘ambush' coaches in the business.

Here in Japan, in the last act of their tenure, their ambition is to spring another stealth attack before going out in a blaze of glory by leading Wales not just to a World Cup final, but to win it.

Gatland pressed the right motivational buttons on Friday when he said that he had “got two games to go as the Wales coach” – with the clear message that he expects his team to book their place in Saturday's World Cup final.

He added: “There are probably nine or ten players who won't be involved in another World Cup so they have got to relish that opportunity and be excited about this. You have got a chance to do something special in your life and these chances come along very rarely, and you have got to grab them with both hands. When you want something bad enough and you really, really want it, then it can happen.” Gatland said also that the Welsh record of four wins in their last four Tests against South Africa “that speaks for itself ” left him surprised they were being written off – but not unhappy.

That is because he and Edwards have made a habit of defying the odds, whether we are talking Gatland's remarkable feat in turning the 2017 Lions into an outfit capable of drawing a series with the All Blacks in New Zealand with only seven weeks in which to do it, or Edwards' exceptional ability to develop ground-breaking defensive systems, both with Wales and Wasps, which have underpinned their success.

In terms of resources or playing numbers to pick from, as Gatland has pointed out frequently this week, the Welsh do not compare with the three nations they join in the last four, , South Africa and New Zealand.

Where they do compare very favourably is in maximising on the players at their disposal by not just coaching them to get better, but by managing frequently to coax something close to superhuman from individuals many coaches who are spoilt for choice would consign to the scrap-heap. Edwards has applied similar principles with Wales that he had at Wasps, where he instigated a blitz defence so that the tackling line advances rapidly with a view to forcing mistakes by shutting down the attacking side's time and space.

“In the last decade, Gatland and Edwards have been the best ‘ambush' coaches in the business”

A variation on the theme is the “umbrella” defence where the press is strongest in midfield with the centres rushing to either smash the ball carrier or threaten to intercept by getting between the opposing fly-half and his outside backs.

Wales have turned it into a formidable weapon, and it is one of the reasons England were shut-out in the second-half of their Six Nations loss in eight months ago.

It is also why the return of Jonathan Davies to the starting lineup against South Africa is so crucial following his absence against .

At outside-centre Davies leads the defensive blitz in much the same way as Edwards utilised Fraser Waters at Wasps. It is their ability to lead the line and communicate with teammates which is crucial, because as well as being high reward, it is high risk.

Poor alignment, or a wellweighted grubber or chip over the top, can lead to the blitz becoming a liability – and, because South Africa will almost certainly operate a similar system, reaction speed and rapid realignment will be a decisive factor.

It is here that Liam Williams has been worth his weight in gold as a sweeper behind the defensive blitz, but following the ankle injury sustained in Thursday's training which ended his World Cup, Leigh Halfpenny will be charged with the same job.

Springbok scrum-half Faf de Klerk predicted that both teams will rain kicks down on the opposing back three – however, Halfpenny has proved his big-match attributes in the sternest of arenas before. It was not just his goalkicking, but also his commanding presence as a sweeper, and in the air, that earned him the man of the series for the 2013 Lions, and if he draws from that then Wales will be well set.

However, when Edwards spoke earlier this week his focus was very much on how a Welsh side respected for their physical resilience will deal with the power and size of the Springboks.

He argued that statistics on the number of missed tackles is not the most important measure of how successful your defence is.

Edwards emphasised instead that the key is knocking the opposition back behind the gain-line, because that ultimately dictates how many points you leak – especially against a side with the physical clout of the South Africans.

“We'll have to muscle-up on the advantage line. They're huge men. But missed tackles are not the biggest indicators.

It is where you win the gain-line – or, as we call it, the ad-line (that matters most). We need to get down to 13 to 15 points (conceded) as we were in the Six Nations, rather than the 18 to 19 points here.”

Tough: Alun Wyn Jones

Edwards added: “It's seize the moment, and I'm into it – you want to be in big games, and there's nothing bigger than a World Cup final.” Edwards believes he has forwards who are also “into it”, and have the resilience and determination to put dents in the gargantuan South African pack at close-quarters, whether it requires double or single tackles.

With many of the Springbok carriers in the super-sized department, whether props Frans Malherbe or Tendai “Beast” Mtawarira, locks Eben Etzebeth and Lood de Jaeger, or back rowers Pieter- Steph du Toit and Duane Vermeulen, there will be a convoy of dumper-truck tackles required.

This desire to dominate the collisions is reinforced by Springbok coach Rassie Erasmus opting again for a six forwards-two backs split on the bench, with a heavy brigade of Malcolm Marx, Steven Kitshoff, RG Snyman, Franco Mostert and Francois Louw ready to rumble if the first wave are repelled.

However, Edwards said he knows just the man for the job, proclaiming Wales captain Alun Wyn Jones as a heart-and-soul leader who will not flinch however big the obstacles.

“He's 6ft 6ins, he's fast, he's unbelievably competitive and he's unbelievably tough. He is a very brave person who sets the example for everybody. I think he is a better player now than he has ever been, and long may it continue. He is one of the best players I have ever coached, without a shadow of a doubt.

“He totally buys into what I want him to do defensively. He competes hard for the ball, he tries to be aggressive in his tackle technique.

It's only probably when he is not there that you realise how good he is.

“The thing about Alun Wyn is it's always what's next, he is always motivated, which is why he is such a fantastic player. Besides his physical prowess and his skills, it's his mental approach which sets him apart.” It appears to be infectious, because Ross Moriarty, whose closerange late try clinched last weekend's 20-19 cliffhanger against the French, typified the Welsh desire to go toe-to-toe with the South African heavyweights.

Moriarty, who slots in at No.8 following Josh Navidi's torn hamstring, said: “I know what their forwards thrive on, which is being physical, and that's what I thrive on as well. Some players go hiding when it gets tough, but I think I get better in those situations.” There will be no hiding places in the Yokohama set-to with the Springboks, and with the Welsh squad wanting to send Gatland and Edwards on their way with the biggest prize of the lot, they will not be looking for any.