In the end it was all very straightforward for Heart of Midlothian. Steven Naismith’s men were always going to be the favourites to progress to the quarter-finals of the Scottish Cup, but there was a sense going into the fixture that the visitors wouldn’t have it all their own way at the Excelsior Stadium. Rhys McCabe’s Airdrieonians have received plenty of well-earned plaudits for the way they approach the game, and Hearts fans could have been forgiven for approaching the tie with a little nagging voice in the back of their heads – particularly when the team’s previous results against the Diamonds were taken into consideration.

The match had the potential to be a banana skin for Hearts, but they made short work of putting any lingering concerns to bed on Sunday evening. By the time the clock hit 21 minutes, the cup tie was over and Hearts’ place in the last eight was all but secured. Early goals from Lawrence Shankland, Kenneth Vargas and Calem Nieuwenhof put Hearts in the driving seat and although Adam Frizzell reduced the arrears towards the end of the first half, there was never any real threat of an Airdrie comeback. The hosts stuck to their principles admirably before Shankland provided the cherry on top with a delightful chip in the second half.

So, how did Hearts surge into such a position of strength in such a short space of time? What were the tactical tweaks that sent the men in maroon racing into such a commanding position? Let’s take a look at those opening 21 minutes.

READ MORE: Hearts reaction: Super Shankland cleans up Airdrie 'banana skin'

Creating space and attacking the flanks

Rather fittingly, Naismith set the team up in a 4-4-2 diamond against the Diamonds, with Shankland operating in the No.10 role and Alan Forrest and Vargas ahead of him. Full-backs Dexter Lembikisa and Alex Cochrane were given license to get forward and provide the team’s width, while Nieuwenhof and Jorge Grant would also drift wide when the opportunity arose.

Airdrieonians were very narrow in their set-up, which meant there was usually a good amount of space for Hearts to attack out wide. They tended to focus down the right and so Lembikisa saw a lot of the ball in decent areas, but the on-loan Wolves man cheaply surrendered the ball far too often. He would usually try and beat his man, only to be easily dispossessed, and his crosses into the box weren't great either.

Cochrane had more joy on the opposite flank. He didn’t see as much of the ball as Lembikisa, but the Englishman rarely gave it away. His choice of pass and its subsequent execution was excellent, as was his assist for the opening goal (more on that later). Further up the park, Forrest and especially Vargas were usually taking up very wide positions off the ball before cutting inside, dragging their markers with them and fashioning more space for the likes of Lembikisa and Cochrane to drive into. Below is a typical example.

The strategy worked perfectly for Hearts’ third goal. Nieuwenhof got the ball on the right-hand side and started to drive up the flank. Ahead of him, Vargas drifts infield to make a bit more space, dragging a defender with him, and the overlapping run of Lembikisa forces another Airdrie defender to cover the space on Nieuwenhof’s outside.

The result was that the Australian was able to make it all the way to the edge of Airdrie’s box before being closed down by an opponent.

A touch inside and a clever dummy later, and Nieuwenhof is in a great shooting position. He makes no mistake to put Hearts 3-0 up, and for all intents and purposes it is game, set and match.

READ MORE: Steven Naismith: Hampden target, what pleased him with win and Halkett update

Shankland drops deep

Hearts’ captain isn’t averse to dropping into midfield to help out with the team’s build-up even when he is the focal point in attack, and as the No.10 against Airdrie, he was doing so constantly, causing McCabe’s side all sorts of problems. His marker would let him run, effectively giving Hearts an extra body in the middle – and they would take full advantage of their numerical superiority.

Take a look at the opening goal. Shankland would of course finish off the move with aplomb, but he was heavily involved earlier on too. It all starts with Shankland receiving a pass from Craig Halkett on the halfway line. He passes it backward to Lembikisa and then drifts wide.

He gets it back and uses his body well to back into the Airdrie man before a clever backheel to Nieuwenhof beats the press.

He can now charge forward, and Airdrie get their press wrong. Two players decide to close Nieuwenhof down, Vargas holds his position out wide further up and all of a sudden, there’s an awful lot of space on the far side.

He times his pass well, releasing it to Forrest who has an opponent breathing down his neck. He hasn’t spotted how much space Cochrane is in, but Grant has. Forrest plays it first time to Grant, and Grant plays it first time to Cochrane.

Airdrie are in real trouble now. Cochrane drives forward before drilling the ball across the face of goal. Look how many options he has. Nieuwenhof attacks the front post, Vargas attacks the back, Forrest waits on the edge of the box, and Grant and Shankland are both in excellent positions. Cochrane has five high-quality options, and each one can easily result in a goal.

The one-touch passing certainly helped Hearts to take advantage of the gaps that opened up, but they would not have appeared in the first instance without Shankland dropping deep to help out. His excellent hold-up play invariably draws multiple opponents towards him and once he shifts it on and they’re caught out, it creates all sorts of issues elsewhere on the park. The opening goal was the best example of the ploy paying off, but he was at it for pretty much the whole game. Quite simply, Airdrie didn’t know how to combat it.

READ MORE: What Rhys McCabe said about Hearts and £5m-6m Lawrence Shankland

Playing on the shoulder

A word, too, for Kenneth Vargas. The Costa Rican now has four goals in his last eight appearances and is adding some welcome consistency to his game. He appears to be growing in confidence week-by-week and although his finish for Hearts’ second on Sunday wasn’t exactly the cleanest goal he’ll ever score, it did demonstrate how dangerous he can be when playing off the shoulder of the last defender.

Take a look at his starting position for his goal. Halkett’s long pass forward is outstanding, but so is Vargas’ positioning. The Airdrie backline is all over the place – the left-back is far too deep – and Vargas required no second invitation to take full advantage.

He times his run perfectly and is in acres of space. His first touch is a bit heavy, but he follows in and gets his reward.

A few minutes later and something similar happens again. Shankland drops deep and plays it to Nieuwenhof, who then dinks the ball down the line for Vargas to latch onto. He’s got a defender in the way but they’ve already committed to the tackle. If the Costa Rican can get past him, there’s nothing to stop him driving at goal.

A deft touch takes Vargas past his man, and now Airdrieonians are in a world of trouble. Grant and Forrest are up in support, and can roll the ball into an empty net if the ball is squared to them.

In the end, Vargas’ touch is a little heavy again, and McCabe is able to get across to snuff out the danger, but it’s another encouraging passage of play from the on-loan forward. His ability to play on the shoulder and burst in behind is one of his greatest assets – we just need to see it a little more often.