Wigan are in fine form at the minute.

A roar goes up as a crowd of Wigan players carry Ethan Ryan in to touch.

You wouldn't know they've just had someone sent off by the way they're playing.

Jai Field knocks on under pressure from Hull KR after Liam Marshall sends in a tame pass as he avoids running in to touch.

Wigan aren't holding back despite being down to 12.

Robbie Hunter-Paul
Former New Zealand international on BBC Two

It's not a big difference to your defensive line when you’re missing one player, it’s just your energy levels that will go.

They still have everything to play for but Hull can smell an opportunity.

Tom Opacic is off for a head injury assessment as Hull KR are, at least temporarily, depleted.

Jimmy Keinhorst is on but Wigan go on the attack.

Image source, swpix.com

Rob Brown: If that's a red card, we might as well all go home!

Callum Thompson: That's a red card all day long for Joe Shorrocks. You can't go in with your shoulder like that in the modern game. That's the reality.

Alastair Hill: Red, yellow, penalty or play on is pretty much irrelevant. However, if the ref gives a red for forceful direct contact to the head why doesn't that mean Mikey Lewis has to go for a HIA?

Polarising! Keep your opinions coming by using #bbcrl

Josh Charnley
Leigh winger on BBC Radio Manchester

I don’t think it’s a red card.

The way that Mikey Lewis has dipped and Joe Shorrocks is set before the tackle.

It’s a talking point.

Wigan are down to 12 but you often play with more desire when you have 12.

Hull KR don’t need to throw the ball around now, just play and it will come.

Well Wigan have got their work cut out, now. They currently have a four-point lead on Hull KR but that Joe Shorrocks red card will have given Matt Peet a headache.

Can the Robins use their player advantage?

Image source, swpix.com

It's not a trip to the bin for Wigan's Joe Shorrocks. It's a straight red card.

Liam Moore sends him off for making contact with Mikey Lewis' chin with his shoulder and Wigan are going to have to play almost the entirety of this second half with 12 players.

Where do you stand on that? Let us know using #bbcrl on social media.

Image source, swpix.com

Joe Shorrocks has just put in a, let's just say, robust challenge on Mikey Lewis.

Replays show he went in heavy with his shoulder and Lewis looks pretty dazed in the aftermath.

This could be a spell in the bin. The replays don't look pretty.

Right then, a big 40 minutes awaits.

Can Hull KR mount a comeback and make it fourth time lucky in a Challenge Cup semi-final?

Or will Wigan seal a sensational final against near neighbours Leigh?

It will be a St Helens v Leeds Rhinos Challenge Cup final at Wembley in a few week's time.

If you missed Leeds' win against Wigan earlier today, don't worry, we have you covered.

Highlights of that victory are below.

Southstander: This is a cracking cup tie so far!

Nick Pinkney
BBC Radio Humberside Summariser

It's very even.

It’s there to be taken in the second half.

Hull KR have to make more of their opportunities.

Both teams have got qualities we haven’t seen yet so we're hoping for a better second half.

Image source, swpix.com

Both sides have looked impressive in attack. Both sides have given away some costly errors.

There's not much in it but Harry Smith's penalty goal on the verge of half-time has given Wigan the advantage.

But you just get the feeling Hull KR aren't out of this yet. The game is still in the balance.

Image source, swpix.com

Harry Smith goes for two and gets the two.

Wigan are four points ahead of Hull KR at the end of a thrilling first half.

Nick Pinkney
BBC Radio Humberside Summariser

That’s a poor decision from Hull KR.

It gives Wigan an easy option to go for the two points.

A silly decision.

Meanwhile at the other end of the field, Wigan look to catch Hull KR on the counter.

Harry Smith sends a kick in on the turnover and Shaun Kenny-Dowall just about regains the ball before Wigan can race on to it.

Shortly after, Wigan are awarded a penalty in kicking range for a ball steal.

Will they go for two?

Robbie Hunter-Paul
Former New Zealand international on BBC Two

As fun as that set was, that was a disappointing end.

There was some scrambling defence by Wigan, a bit of desperation, but you have to take your hat off to them.

No sooner do Wigan win the ball back from Brad Schneider's forward pass do they lose the ball cheaply inside their own 10.

Hull KR look dangerous right now but a succession of attacks come to nothing as Wigan put in some supreme defence to hold ground.

This is such a great cup tie. Both sides giving both barrels, errors being punished, defences holding firm.

Much like Louis Senior's opener for Hull KR, the Robins prosper from a Wigan knock-on just past 30 metres out.

KR whip the ball about well as they try to catch Wigan out with speed but Brad Schneider's long-range pass to Mikey Lewis is judged to be forward.