The teams are coming out now. Game on!

Paul Grayson
Ex-Northampton and England fly-half on BBC Radio 5 Sports Extra at the Stade Atlantique

This is a fantastic stadium. The fans are close to the touchline and it holds the noise really well.

The big stadiums make it a great experience.

You go here because your in the big games.

Chris Jones
BBC rugby union correspondent on BBC Radio 5 Sports Extra at Stade Atlantique

It is starting to dry up.

Image source, Rex Features

Thumbs up for Bordeaux, thumbs down for Bath.

Damien Penaud, France's all-time leading try-scorer continues in an outside centre role that he has reprised in recent weeks for Bordeaux-Begles.

The 29-year-old wing, who was left out of France's squad for the Six Nations, played in midfield at the start of his career.

Matthieu Jalibert and Finn Russell will face off in a duel of play-making fly-halves.

The battle in the front row is also set to be key. Bordeaux-Begles' first-choice loose-head prop Jefferson Poirot is banned for the match, giving Bath's South Africa international Thomas du Toit the chance to target the less-experienced Matis Perchaud.

The hosts do have 23 stone-plus Ben Tameifuna on the bench to supplement their set-piece in the second half.

Bordeaux-Begles: Rayasi; Uberti, Penaud, Moefana, Bielle-Biarrey; Jalibert, Lucu (c); Perchaud, Lamothe, Sadie, Palu, Coleman, Bochaton, Woki, Gazzotti.

Replacements: Barlot, Boniface, Tameifuna, Cazeaux, Vergnes-Taillefer, Matiu, Retiere, Reus.

Image source, Getty Images

Kick-off has been delayed by 10 minutes.

Chris Jones
BBC rugby union correspondent on BBC Radio 5 Sports Extra at Stade Atlantique

I have never seen this before, Bordeaux are doing a full lap of the pitch to get the crowd going.

The rain continues to bucket it down.

Will this help Bath?

Send us your thoughts on the game.

Image source, Rex Features

Mike Henson
BBC Sport

Henry Arundell's favourite childhood memory of Bath is of another semi-final.

Back in 2015, as a 12-year-old, he and his season ticket-holding family were at the Recreation Ground cheering on a demolition of Leicester in the Premiership play-offs.

Arundell, now 23, and his modern-day Bath team have another semi-final to negotiate. It will be considerably tougher than that rout of Leicester.

"That was an awesome day - I remember that team so well," Arundell told BBC Sport. "There was George Ford at 10, which is a bit of a weird one now playing with him for England.

"But also Kyle Eastmond, Jonathan Joseph, Anthony Watson - another who I have played with at England, again weird.

"Tom Dunn and Charlie Ewels were part of that squad and are still here.

"I was just a child who loved rugby and dreamed of one day being in this scenario, so, yeah, it's pretty cool."

Read more here.

Image source, Getty Images

Former England fly-half Paul Grayson is in Bordeaux for BBC 5 Live Sports Extra.

Check out his thoughts below.

"Bordeaux will score points, it is how you respond," he said.

Chris Jones
BBC rugby union correspondent at Stade Atlantique

After biblical thunderstorm this lunchtime, the clouds did lift for a while, but there remains a thunderstorm warning in the Bordeaux area.

Just like in the Lions third Test in Sydney, if there is lightning within a 10km radius of the stadium, the players will come off and the match will be paused.

It's just started absolutely hosing down...

First-choice scrum-half Ben Spencer has recovered from injury to take his place in Bath's starting line-up.

Spencer has been suffering with a shoulder injury and hasn't played since 10 April's last-eight win over Northampton.

After South African Bernard van der Linde had ankle surgery to leave Tom Carr-Smith as the only senior specialist, Bath called teenager Isaac Mears into the senior squad to plug a potential hole at nine.

Bath do have absentees elsewhere in their backline however.

Centre Max Ojomoh and wing Joe Cokanasiga, rated as "touch and go" by boss Johann van Graan earlier in the week, have failed to recover from knee and leg knocks respectively.

With midfielder Cameron Redpath also out, Louie Hennessey, who impressed on the wing against Northampton at the weekend, starts at 13, while Ollie Lawrence shifts to inside centre.

Bath: Carreras; Arundell, Hennessey, Lawrence, Muir; Russell, Spencer (c); Obano, Dunn, Du Toit, Roux, Ewels, Bayliss, Pepper, Barbeary

Replacements: Tuipulotu, Van Wyk, Sela, Hill, Underhill, Carr-Smith, De Glanville, Reid

Image source, Getty Images

Chris Jones
BBC rugby union correspondent at Stade Atlantique

Bath fans have travelled in their thousands, with those we have spoken to around town buzzing at being back at this stage of the Champions Cup for the first time in two decades.

Their task, however, is daunting. While Bordeaux have had a fitful season in the Top 14, on the European stage they have been irrepressible, and with Matthieu Jalibert and Louis Bielle-Biarrey, they possess two of the greatest attacking players in the world. If Bath are loose in possession and gift UBB easy turnover ball in front of 40,000 passionate fans, it could get messy.

But this is an outstanding Bath group who have been building for this occasion for years. With Jefferson Poirot injured, they will target the Bordeaux scrum, and if they can put the hosts under pressure, they certainly have the potential to pull off something special. They will miss Max Ojomoh in the midfield, but UBB are without star centre Nicolas Depoortere, while the Bordeaux coach Yannick Bru is banned from any team involvement.

It's a contest laden with intrigue and excitement and should showcase the very best of this competition.

Bordeaux host Bath at a sold-out 42,000-capacity Stade Atlantique for a place in the Investec Champions Cup final.

It does not get much bigger.

Can Bath do it? This is their first Champions Cup semi-final in 20 years.

Leinster await in the final on Saturday, 23 May in Bilbao.