Monaghan make their numerical advantage count immediately as Andrew Woods curls over his second point of the afternoon.

It's a nightmare opening for Louth, who now trail by four with only seven minutes on the clock.

Image source, Getty Images

A huge early moment at Croke Park.

Sean Callaghan is shown a straight red card after a high shoulder challenge on Monaghan's Ryan McAnespie, reducing Louth to 14 men with just over six minutes played.

It's an enormous setback for the Wee County, who already trail by three points.

Louth carve Monaghan open with some slick passing and Conor McCarthy looks set to race through on goal.

But Stephen O'Hanlon produces a superb last-ditch intervention, getting a crucial hand in to deny the danger at the final moment and win turnover.

Sam Mulroy has Louth's first scoring chance from a free between the 45m and 65m lines, but his effort drifts wide.

The Wee County are still searching for their opening score after five minutes.

Monaghan threaten again after another effort from distance drops short, but Louth fail to deal with it.

Killian Lavelle reacts quickest to keep the attack alive before Andrew Woods finishes the move with a composed point.

There were alarm bells ringing for Louth, with a goal chance appearing to be on the cards before Woods opted to take the point.

Monaghan immediately win the resulting kick-out and make the pressure count as Conor McCarthy lands a superb two-point score to open the Farney men's after two minutes.

Monaghan register the first effort of the afternoon, but late replacement Oisin McGorman pulls his shot wide of the posts.

Referee Sean Hurson throws the ball in and the opening quarter-final of the day is under way.

John McGovern
BBC Sport NI contributor

Two of this summer's surprise packages meet in today's opening quarter-final at Croke Park.

Louth booked their place in the last eight by doing what Monaghan could not in May – defeating Ulster champions Armagh in Round 2B thanks to Sam Mulroy's dramatic late goal.

Monaghan, meanwhile, have enjoyed an impressive run of their own, upsetting Connacht champions Roscommon before sealing their quarter-final place with victory over Leinster winners Westmeath in Round 3.

Neither county began the championship among the favourites for the Sam Maguire Cup, but both have upset provincial champions along the way. Now, one will move to within a single game of an All-Ireland final.

Tonight's All-Ireland semi-final draw will take place after today's quarter-finals, with Kerry and Mayo already through to the last four.

There can be no repeat pairings from any earlier round of this year's All-Ireland Championship in the semi-finals, meaning two potential ties have already been ruled out.

If Louth and Dublin both progress, they cannot be drawn together after meeting in Round 1, while a Monaghan victory would rule out a semi-final against Mayo for the same reason.

Victory for Galway and Louth, however, would leave the semi-final draw completely open, with all four remaining counties able to face one another.

Odhran Crumley
BBC Sport NI at Croke Park

Image source, Getty Images

It's the news every Monaghan fan feared: Rory Beggan is out of today's game through injury.

A huge blow for Gabriel Bannigan's side. His kick-outs, two-point threat and leadership are irreplaceable, and his absence could prove decisive.

The momentum has undoubtedly swung in Louth's favour.

The big news coming from Croke Park is that Rory Beggan is out of today's clash through injury and Jamie Mooney will wear number one.

Shane Hanratty also comes into the side with Karl Gallagher also missing out through injury.

Monaghan are forced into further changes before throw-in. Karl Gallagher and Stephen Mooney drop out through injury, with Ryan McAnespie and Oisin McGorman coming into the starting line-up.

Louth are unchanged from the side that stunned Armagh in round 2A, with Gavin Devlin keeping faith with the XV inspired by Sam Mulroy's dramatic late winner in Inniskeen.

Ciaran Keenan and Padraic Tinnelly come into the matchday squad in place of Sean Reynolds and Cormac McKeown, while Peter Lynch, Eoghan Callaghan and Dermot Campbell remain sidelined through injury.

Louth: Niall McDonnell; Emmett Carolan, Donal McKenny, Daire Nally; Conall McKeever, Dara McDonnell, Craig Lennon; Paul Mathews, Sean Callaghan; James Maguire, Sam Mulroy, Conor Grimes; Kieran McArdle, Ciaran Downey, Ryan Burns.

Subs: Tiernan Markey, Ciaran Byrne, Tommy Durnin, Conor Early, Leonard Gray, Ciaran Keenan, Conall McCaul, Conor Mac Criosta, Tadhg McDonnell, Padraic Tinnelly, Anthony Williams.

Monaghan: Jamie Mooney; Ryan Wylie, Killian Lavelle, Dylan Byrne; Dessie Ward, Ryan O'Toole, Conor McCarthy; Micheal McCarville, Oisin McGorman; Aaron Carey, Micheal Bannigan, Stephen O'Hanlon; Jack McCarron, Andrew Woods, Ryan McAnespie.

Subs: Kian Mulligan, Fionan Carolan, Robbie Hanratty, Cameron Dowd, Shane Hanratty, Stephen Mooney, Darragh McElearney, Thomas Hughes, Max Maguire, David Garland, Tom Doherty.

Image source, BBC Sport

Image source, Getty Images

Welcome to our final day of quarter-final coverage as we bring you today's All-Ireland Senior Football Championship double-header from Croke Park.

Yesterday, Mayo booked their place in the semi-finals with a 0-23 to 0-18 victory over Cork before defending champions Kerry survived a stirring Tyrone challenge to prevail 2-25 to 0-27.

Today, neighbours Louth and Monaghan battle it out for the third semi-final berth before Dublin face Galway in a highly anticipated clash to complete the last-eight action.

We'll bring you all the build-up, live updates and reaction from both games as we discover the two counties who will join Kerry and Mayo in the All-Ireland semi-finals.

Thanks for joining us. Enjoy!