Scotland vs. Ireland: 5 Key Battles That Will Shape 2015 Six Nations Clash

Ireland's defence of the Six Nations title will come to a climactic close in Edinburgh this Saturday, where Joe Schmidt's side end their tournament against Scotland with the aim of retaining their European crown.

The reigning champions will have to wait until England and France have finished their duel at Twickenham in Saturday's evening fixture to find out if their defence has been successful.

Currently second in the table, Ireland need to pile the points on Scotland if they're to have a hope of surmounting the English should Stuart Lancaster's men beat Les Bleus.

That being said, Ireland's only focus will be on their fixture and the individual battles awaiting them at Murrayfield. Read on for a roundup of which key collisions will have a dramatic effect on Saturday's tie.

1. Stuart Hogg vs. Rob Kearney

The northern hemisphere is somewhat blessed with full-back talent at the moment, and two British and Irish Lions are sure to lay on a feisty encounter when Stuart Hogg welcomes Rob Kearney to Edinburgh.

Both Hogg and Kearney played second fiddle to Leigh Halfpenny on the 2013 tour, but each have shone in their own quantities throughout this tournament, setting up what should be a magnificent Week 5 clash.

As only a man of his stature can, Kearney has dominated the airwaves once again for Ireland and risen to be an extremely useful kick-chase asset for Johnny Sexton and Conor Murray.

For Hogg, though, his individual accomplishments have pointed him out as an asset clearly above the average among his team-mates, the figure looked upon for inspiration in Vern Cotter's back line time and time again.

In the end, Kearney's fortune in having a higher standard of player surrounding him will likely make the difference, but Hogg is nevertheless a spark capable of sparking magic with ball in hand.

2. Euan Murray vs. Cian Healy

A fit-again Cian Healy is primed for his first start of this year's Six Nations after finally making a full recovery from the hamstring tear that kept him out of last year's November series.

Euan Murray will have mixed feelings about the change in Schmidt's lineup; Scotland's tight-head may be displeased to see a player as talented as Healy coming in, but Jack McGrath was by no means showing poor form prior to his drop to the bench.

Healy's much-awaited return to Schmidt's XV will be a topic of some focus, and Murray may fancy his chances against an opponent slightly lacking in playing time, despite coming off the bench in Ireland's last three games.

It will also be a day of great significance for Murray, who will overtake Allan Jacobsen as Scotland's most capped prop in his 66th appearance, a fitting occasion to overcome his opposite man and inspire an underdog victory.

3. Mark Bennett vs. Jared Payne

David Rogers/Getty Images

Jared Payne's start to life in the green of Ireland has been greeted with a mixed response, some seeing his performances thus far as safe and reliable, while others have sought more of the sensational.

The New Zealander may not be the second coming of Brian O'Driscoll, but last week earned the criticism of RTE pundit George Hook, who labelled Payne a "second-rate foreign player" in the wake of last Saturday's defeat to Wales.

Per the Irish Independent (h/t Balls.ie), Payne has responded with as much maturity as his predecessor O'Driscoll, though, saying: "Everyone is entitled to their own opinions. I didn’t hear it all. I haven’t really watched any of that sort of thing."

The Ireland centre will need to show that very fortitude in Edinburgh, too, as Mark Bennett is sure to give him stiff competition after impressing in Scotland's loss to England at Twickenham.

The outside centre scored Scotland's only try in that fixture, but did miss a disappointing three tackles, according to ESPN Scrum, which Jonathan Joseph made sure to take advantage of.

Payne, on the other hand, missed just one of his tackling attempts in Cardiff and will be hoping to emerge triumphant over Bennett, proving his critics wrong in the process.

4. Jonny Gray vs. Paul O'Connell

Dan Mullan/Getty Images

There's a small chance this weekend's fixture in Edinburgh could be Paul O'Connell's last in the Six Nations, having already noted his potential retirement after this year's Rugby World Cup, per Johnny Watterson of the Irish Times.

How fitting it is, though, that as one illustrious international lock's career nears its end, another is just getting its start at Murrayfield, with Scotland's Jonny Gray frequently raising the bar of his personal standards.

It wasn't long ago the younger of the Gray siblings was known more as "brother to fellow lock Richie," but the Glasgow Warriors starlet now sits as Cotter's best second-row option and a firm adversary for O'Connell.

Having just celebrated his 21st birthday, Gray is a full 14-and-a-half years younger than O'Connell, but what he lacks in experience the Scottish starlet more than makes up for in potential.

O'Connell's handling skills were a joy to watch at times against Wales, a key component in several phases of exemplary ball retention, but Gray is another who likes to muck in get the physical work done.

Their battle as two well-conditioned, athletic lock figures promises to make for a barbaric meeting both in the loose and at the set piece, but both have their finer touches of class and are more than mere brutes.

5. Greig Laidlaw vs. Conor Murray

Wales' defence against the kick-and-chase was a crucial aspect in their ability to fend off Ireland's assault in Week 4, so much so that scrum-half Murray only attempted two nudges with the boot in total.

He'll come up against Greig Laidlaw in Edinburgh this Saturday, and Cotter's leader figure is motivated to bring his side a first win of the 2015 Six Nations and avoid this year's wooden spoon, per ESPN Scrum:

"

Well yeah. We don't want to do that, do we? As players that is certainly not what we set out to do. 

But we have an opportunity this weekend to make sure we [don't finish with the Wooden Spoon]. That's all we can do this year unfortunately. We will go out there and give absolutely everything to try and avoid [another defeat].

It's a huge game for us but I know the boys are absolutely desperate to get out there, put in a good performance and come away with a win.

"

The armband-wearer will be extremely preoccupied in his head-to-head with Murray as well. The Irish No. 9 is renowned as a sniping talisman, one who'll punish his counterpart for any lapses in concentration Laidlaw happens to display, never mind marshalling the rest of his troops.

Laidlaw also has the extra burden of his kicking duties to worry about, making his job that much harder as he looks to disrupt Murray's momentum.

Each of these scrum-halves can be game-changers for their respective teams, and we may see Murray move back to the kicking priorities utilised so brilliantly against England this weekend.