James McClean has scored four of the Republic's last five away goals in competitive fixtures, including the winner in their last visit to Wales in October 2017.

But he is out today after injuring his wrist in training.

He broke the news via his Instagram story.

Wales defender James Chester says they face an "exciting time" under new boss Ryan Giggs.

Giggs replaced Chris Coleman, who left after Wales failed to qualify for the World Cup.

"Our experience of the Euros was one of the main reasons not reaching the World Cup was so difficult to take. The success we'd had made us hungry for more so to miss out on the biggest stage was tough," said the Aston Villa player.

"The success we had with [Coleman] and how well we all got on with him, we were all sad to see him go and we weren't sure what the future would bring.

"But it's an exciting time with the new manager and with a lot of young players and talented players in the squad, it can only be exciting for us and something to look forward to."

Danny Gabbidon
Former Wales defender on BBC Radio 5 live

Ryan Giggs has gone bold with his attacking line-up and he has placed a lot of faith in these young players. Maybe he is trying to keep the senior players on their toes.

Today is the first day of the Nations League. Here's a list of the fixtures (all 19:45 BST kick-offs unless otherwise stated).

A1

Germany v France - there will be a separate dedicated live text for this game starting at 19:30 BST.

B1

Czech Republic v Ukraine

B4

Wales v Republic of Ireland

C3

Norway v Cyprus

Slovenia v Bulgaria

D1

Result - Kazakhstan 0-2 Georgia

Latvia v Andorra

D4

Result - Armenia 2-1 Liechtenstein

Gibraltar v FYR Macedonia

Image source, Getty Images

Republic of Ireland captain Seamus Coleman says he will not be thinking about his leg break as he prepares to face Wales again.

The Everton right-back was out for almost a year after following a horrific tackle by Neil Taylor in a World Cup qualifier in Dublin last March.

This is his first competitive international game since then.

"That night in Dublin is something that I'm not really thinking about, it's 18 months ago," Coleman said.

"I've not forgotten about it, but it's something from the past.

"These games are a little bit different to playing other nationalities because you do know the players you're up against, but they are still great games to play in."

Dafydd Pritchard
BBC Sport Wales at Cardiff City Stadium

Wales’ rematch with the Republic of Ireland is one rich in sub-plots and rivalries.

This will be Ryan Giggs’ first competitive match in charge of Wales, against the same opponents of his predecessor Chris Coleman’s final competitive fixture.

In fact, that meeting in October last year was Wales’ most recent competitive outing, a 1-0 defeat which ended their World Cup hopes and took the Irish into a play-off, which they lost to Denmark – the other team in this Nations League group.

James McClean, who scored the winner in Cardiff last year, is among a handful of Irish players missing tonight.

But they do have captain Seamus Coleman back after missing the end of the World Cup qualifying campaign because of the double leg break he sustained in Dublin 18 months ago - in a tackle by Wales’ Neil Taylor.

BBC Radio 5 live

You can listen to live radio commentary on this game on BBC Radio 5 live, or via the top of this page. Build-up has just started.

You can also watch highlights of the game later on BBC One Wales - that starts at 22:40 BST.

One for the squad number purists - Sheffield United defender John Egan is among the Republic of Ireland subs today - with the number 10 jersey.

Republic of Ireland boss Martin O'Neill wants the Denmark situation to be sorted out so they can play a strong team against Wales.

"If it does develop this way there would certainly be a degree of unfairness about it," said O'Neill.

"I think everyone would accept that if Denmark play players from lower divisions against Wales then it certainly gives them a massive advantage.

"I think Uefa probably should [act], and will as well, if it develops in the direction that it looks as if it is going.

"It wouldn't be fantastic news for the competition."

Image source, Getty Images

Image source, Reuters

The other team in this group are Denmark - who face Wales on Sunday.

The Danes could field a team of lower league and futsal players - as they did in yesterday's 3-0 friendly defeat by Slovakia - because of a dispute between the players and their FA.

However, a Danish Football Association spokesman told BBC Wales today it is prepared for talks with senior players that could end their dispute.

"What sort of team we'll face we don't know," said Wales boss Ryan Giggs previously.

"There's a bit of me thinks they'll sort it out but every day that looks more and more unlikely - but we've got a big game on Thursday so all my concentration is on that.

"I'm keeping an eye on the situation but the concentration is on tomorrow's game. I'll deal with that after the Republic of Ireland game."

Right, so what do you think of this Nations League? Better than friendlies?

If you have any questions about it, tweet us at #bbcfootball or text 81111 and we'll try to answer them (if we can work out the answer ourselves).

Or if you think you understand it fully, then try to explain it all in one tweet and we'll publish the best ones.

I'm not going to lie to you - it's complicated. There's too much detail to explain it fully in one entry here - so I'll just let you know about this group.

Denmark, Wales and the Republic of Ireland are the three teams in Group 4 of League B - playing each other home and away between now and November.

The winners of this three-man group will go into a Euro 2020 play-off in March 2020 - where they will face three other teams in League B, which is sort of Russia, Austria, Czech Republic level - in a semi-final and final.

However if the winners of this group qualify for Euro 2020 directly through the normal qualifiers, then the next highest ranked team in the league take their play-off place. It's possible that the Republic of Ireland could lose all these four games 5-0 - and still qualify for the play-offs.

Also the team who win this group get promoted for the next Nations League in two years - to the level involving Spain, Germany etc. And the team who finish bottom get relegated to Hungary, Greece, (sorry) Scotland level. So only one of these three teams will be in League B next time.

I'm hoping it's going to be like a new board game where it makes more sense as you just get on with it. Here's a Uefa video that sort of explains it.

Richard: Gunter on the bench???

Simon: Really looking forward to the international matches. #yawn

Dafydd Pritchard
BBC Sport Wales at Cardiff City Stadium

Ryan Giggs picks a young, attacking team for his first competitive game in charge.

Chris Gunter's run of 63 consecutive starts comes to an end as he's replaced by Connor Roberts. Chelsea teenager Ethan Ampadu and Bournemouth youngster David Brooks also start, while Brentford’s Chris Mepham is preferred to James Chester at centre-back.

Gareth Bale returns after missing May’s friendly draw with Mexico while he was scoring a spectacular bicycle kick in Real Madrid’s Champions League final win over Liverpool.

Wales XI: Hennessey; Roberts, Williams, Mepham, Davies; Allen, Ampadu; Brooks, Ramsey, Lawrence; Bale.

We'll bring you full Wales team news in a minute but the big news is arguably 17-year-old Chelsea defender Ethan Ampadu making his competitive Wales debut - and Chris Gunter being benched.

Preston striker Callum Robinson makes his Republic of Ireland debut after declaring for the country in March. Jon Walters starts despite only making one league appearance in 2018.

Seamus Coleman captains the side.

Robbie Brady, James McCarthy, Shane Long, Scott Hogan and Sean Maguire are all injured.

Harry Arter is out after falling out with Roy Keane and Declan Rice, who can also play for England, is considering his international future.

Image source, ,

Tonight is the first competitive game - and the first home match - of Ryan Giggs' reign as boss.

So far they have beaten China 6-0, lost 1-0 to Uruguay and drawn 0-0 with Mexico - all abroad.

BBC Sport Wales' Chris Wathan has written a piece about that.

Read it here.

Image source, Getty Images

Last time Wales met the Republic of Ireland, their World Cup dreams were ended by the Irish.

The Republic's 1-0 win in Cardiff sent them to the World Cup play-offs (which they went on to lose) and broke Welsh hearts.

The sides meet again in tonight's Uefa Nations League opener.

"I don't see it as a grudge. We're professionals and there are a lot of reasons why we want to win this game," said captain Ashley Williams.

"It is part of my job if there is anything in their minds about [revenge] - no, get it out of your head," said new boss Ryan Giggs.

But do we believe them?