TOKYO, 13 Oct - All metres on a rugby pitch might be the same length but some are more difficult to get across. It is significantly easier to cross the halfway line than it is to cross the much more heavily fortified try-line. The reason is pretty simple: at halfway, defences will drop back at least two defenders to cover the kick, while at the try-line all 15 are blocking your progress.
Part of the reason for Ireland's heavy victory over Samoa was their ability to convert chances when they were close to the Samoan line. Ireland have not played with an expansive gameplan during this tournament; they have passed just 1.2 times per ruck, ahead only of Russia. What they do have is power. In the wet and wild conditions in Fukuoka, a simple gameplan marshalled by skipper Rory Best, above, and huge forward power overcame a first-half red card.
The problem with attacking so close to the gainline is that you have all the defenders in the defensive line. The problem with defending with your heels on the line is that just tackling is not enough; you need to drive the attacker backwards.
One way to get over the try-line when you are close is to use power. At one minute in the footage, Tadhg Furlong hits a line just five metres out. He is hard to stop when he knows he needs to carry the ball for only five metres. Remember, even a successful tackle, as Filo Paulo shows, is not enough to stop a try being scored from this close to the line.
At 2.03 we can see the difficulties of defending a scrum. With a very narrow blindside, as Samoa have here, you usually want to have a defensive winger, a scrum-half, and the blindside flanker defending the blindside. If the scrum is turned, as it was here, it removes the blindside flanker.
That forces the defensive scrum-half to make a choice. Does he drift out and allow the attacking scrum-half a clear run at the line or does he stay close to the scrum and hope he can get across to do the defending if the ball is passed?
Dwayne Polataivao stays close to the scrum but when the ball is moved there is a miscommunication between him and winger Ah See Tuala. Tuala drifts, Polataivao does not, and Johnny Sexton goes straight through the middle of them.
At 2.15 Conor Murray showed one of the benefits of attacking close to the line. The defence is exceptionally close to you but they have to tighten around the breakdown to drive the attacker backwards.
Long flat passes are incredibly risky because a defender can just stick out an arm and intercept. If they are successful they remove all the defenders between the passer and the receiver. Murray allows Jordan Larmour to cross unopposed thanks to a perfect but high-risk pass.
Ireland overcame a red card thanks largely to their ability to convert the attacking opportunities they had close to the Samoa line. That efficiency will serve them well as they look forward to the quarter-finals.