The rules of engagement - tighthead v loosehead

What's the difference between tighthead and loosehead prop?

Can props play either side? Who is the key figure at the scrum, both attacking and defensive?

Here are the answers to some of those often-asked questions.

* First off, former All Black tighthead prop John Drake says the most basic rule of scrummaging is go in straight.

During his days with Auckland and the All Blacks in the 1980s, irrespective of whether the opposition were East Coast or France, his front rows always kept it simple for the first few scrums to feel out their opposition before sorting out a strategy to gain the initiative.

* For a scrum where your team has the put-in:

The loosehead is the key, providing a bridge for his hooker to get a clear view of the ball coming in, keeping the aggressive tighthead opponent at bay. The tighthead is the anchor, ideally getting lower than his loosehead opponent, but essentially a stabilising figure.

* For a scrum where the opposition have the feed:

The tighthead and hooker combine to attack either the opposing hooker or loosehead, trying to create a two-on-one scenario. The loosehead prop is not that relevant, but the bottom line is you are trying to destabilise one of the opposing front row.

* How the techniques differ:

The two props can have different physiques and are using different muscle groups. The key for both loose and tighthead props is their inside leg, the right for the loosehead, the left for the tighthead. That foot is known as the base foot and if it moves it is likely to be no more than a few centimetres forward. The hooker's base foot is always his left as he's hooking the ball with his right. Feet, like a golfer addressing the ball, should be about the same width apart as the shoulders.

* The ideal heights:

Long-held convention is that the tighthead should be about 1.83m (6ft) to 1.88m (6ft 2in), the hooker about the same or slightly shorter and the loosehead about 1.78m (5ft 10in), although Carl Hayman and Andrew Sheridan give the lie to that. The tighthead should hit the scrum fractionally before his hooker and loosehead. On the danger issue, if a scrum collapses, broadly speaking the loosehead is less at risk of injury as he has open space outside his left ear.

* Which is the harder side to prop?

Generally, the loosehead needs to be stronger and his technique must be spot on, according to Drake, who admits he found it a hard job to master. The tighthead needs significant mental toughness as all the weight of both packs comes in on the No 3. Drake says it feels like being in a pressure cooker, and lasts maybe four or five seconds.

* Is it easy to play either side?

Drake says no. For reasons of technique and physique, players who can do both equally well are rare.