Steve Tandy has opted for size and power in midfield and Wales must now show they can be a serious team

The honeymoon period is over for Steve Tandy and his coaching team. The time for progress and encouraging performances is giving way to a more pressing demand for results.

There have been signs of improvement over the past 12 months, particularly during the closing stages of the Six Nations, but patience will only stretch so far. Saturday's Nations Championship meeting with Japan in Cardiff is a game Wales simply have to win.

Japan are not among the upper echelons of international rugby and, playing in front of their own supporters at the Principality Stadium, Wales should have more than enough quality to see off Eddie Jones's side. Anything less would represent a significant setback.

The most persistent criticism of Steve Tandy's reign so far has centred on attack coach Matt Sherratt's determination to deploy a second playmaker at inside centre. You can follow Tandy's press conference today here.

Joe Hawkins and Ben Thomas have been the principal occupants of the No. 12 jersey, but the approach has yet to deliver the desired results.

Sherratt's ambition to give Wales greater attacking shape, width and variety is understandable.

The problem is that, too often, the backline has been left playing on the back foot, struggling to generate momentum or get over the gain-line.

There has long been a perception that Wales lack the physical presence and penetrative threat required in midfield.

Being a gifted footballer is one thing, but an international inside centre must also be able to withstand the collision, win the physical exchanges and create front-foot ball.

Look at the leading nations and there is a common theme. South Africa have Damian de Allende, Ireland rely on the abrasive Bundee Aki, while New Zealand have developed a different kind of threat in Jordie Barrett.

Barrett offers the distribution and vision of a second playmaker, but he is far from a lightweight operator.

He is a powerful, direct runner who consistently challenges the gain-line and gives his outside backs a platform from which to attack.

Wales have now moved closer to that model with the selection of Max Llewellyn and Eddie James in midfield.

Llewellyn missed large chunks of last season through injury before returning for the summer campaign, but he has since been showing his quality at Gloucester.

At 6ft 6in and more than 16st, the 27-year-old has the physical dimensions to cause opponents real problems. The challenge now is to make that size and power count against Japan.

Llewellyn is an intelligent rugby player with all the attributes to make an impact at Test level, but his primary responsibility must be to get Wales over the gain-line and provide a platform for those outside him.

He also needs to bring Eddie James into the game as often as possible.

There are plenty of former players who would argue that James should be wearing the No. 12 jersey, given the Scarlets centre is arguably the most effective midfield carrier in Welsh rugby when it comes to making ground through contact.

James is one of Wales' most potent attacking weapons. If the midfield can establish dominance over the gain-line, the likes of Louis Rees-Zammit and Blair Murray will have opportunities to exploit the space out wide and punish Japan.

The outside-half call

There may also be a few raised eyebrows at the decision to select Sam Costelow at outside-half ahead of Dan Edwards.

The Ospreys playmaker started nine of Wales' 11 Test matches last season, although Costelow spent a significant portion of the campaign sidelined through injury.

The Scarlets fly-half, however, produced arguably the finest individual performance by a Welsh No. 10 last season in the narrow defeat to Scotland. Had he remained on the field for the full 80 minutes, Wales might well have emerged with victory.

Costelow arguably offers greater cohesion to the backline. He likes to play flat to the gain-line and has the distribution and vision to bring others into the game, qualities that could prove particularly valuable with two powerful centres outside him.

His lack of consistency at international level, partly a consequence of recurring injuries, remains a concern.

But this is an opportunity to establish himself and demonstrate why he could be the right man to get the best out of Wales' new-look midfield.

Remarkably there are no Ospreys in the starting XV for the second time in four months.

Test matches, however, are still won and lost up front, and there will be a huge onus on Wales' pack to establish dominance against Japan.

There are 283 caps of experience in the Welsh eight, with sufficient physicality and know-how to get the upper hand in the forward exchanges. Wales should be looking to impose themselves from the outset.

The selection of Nicky Smith ahead of Rhys Carre and Archie Griffin over Tomas Francis may raise a few eyebrows, but there are sound reasons behind both decisions.

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Carre has managed only one appearance for Saracens this season because of injury, while Smith offers a more destructive presence at scrum time. Carre, meanwhile, should provide a significant impact off the bench with his ball-carrying ability.

At tighthead, Griffin offers more around the park than Francis, although he does not quite match the veteran's scrummaging strength. It is a selection that places greater emphasis on mobility and work-rate around the field.

Ultimately, Wales have the experience, physical presence and attacking firepower to win this contest comfortably. Now they need to translate that potential into a performance and, more importantly, a result.

Wales: Blair Murray; Louis Rees-Zammit, Eddie James, Max Llewellyn, Josh Adams; Sam Costelow, Tomos Williams; Nicky Smith, Dewi Lake (c), Archie Griffin, Dafydd Jenkins, Ben Carter, Alex Mann, Jac Morgan, Aaron Wainwright.

Replacements: Ryan Elias, Rhys Carre, Tomas Francis, Teddy Williams, James Botham, Reuben Morgan-Williams, Dan Edwards, Louie Hennessey.