To succeed at the top, a 21st Century rugby team requires more than just the efforts of the 15 men on the pitch.
Here, BBC Sport examines the roles of the rugby specialists you don't get to watch on TV.
VIDEO ANALYST: Analyses the team's performance in their previous match and watches the opposition's last encounter to help formulate game plans.
The video analyst compiles tapes of recent footage of any players, teams or tactical moves requested by the coaches and his recordings enable the squad to make a detailed assessment of their display.
They can also provide tapes to help individual players work on the weaknesses in their own games.
VISUAL AWARENESS COACH: Used by some teams in their preparations for the World Cup to maximise players' spatial awareness on the field.
Using 'visualisation' techniques, individuals are encouraged to make themselves aware of all the options available to them in a variety of game situations, both in attack and in defence.
THROWING COACH: Works mainly with the hookers in the squad to perfect their throwing technique at the set piece.
Focusing on the line-out, the throwing coach aims to ensure that every throw has the maximum chance of being accurate and hitting its intended target.
TEAM DOCTOR: A full-time member of the back-up team throughout the week preceding matches, the doctor provides "private 24-hour medical cover", according to Scotland team doctor James Robson.
He explains: "Prior to games our role is to react quickly to treat injuries as they happen and stem illness to prevent it spreading through the squad.
"During a game the game I'm most frequently called upon to attend and assess collision injuries.
"We have to make a quick decision whether a player will recover in a few minutes or they will become a liability and risk sustaining further serious injury by staying on.
The doctor also has the final call over whether a player starts a match or continues in a game after injury, although many make the decision in consultation with the player, physios and coaches.
FITNESS COACH: Responsible for the physical fitness of the whole squad, the fitness coach tailors training programmes to the differing needs of forwards and backs.
The coach's target is to have every player in the team at his physical peak for each match.
It is also his duty to ensure that players have appropriate physical training regimes for both pre- and post-match to avoid unnecessary injuries being incurred due to not sufficiently warming up or down.
CHEF: Prepares food according to nutrition instructions from the coaches and fitness instructor.
In the modern era, players' eating habits are a vital part of the build-up to a match and the chef must ensure that the squad receive a balanced diet and sufficient quantities of food.
Players must consume enough energy-rich foods such as carbohydrates on the eve of the match and also be provided with match day meals and eating routines that can easily be digested before the match begins.
KIT TECHNICIAN: If a flanker is missing a sock, or a prop's shirt rips to shreds in a scrum (a far more frequent occurrence in the era of the skin-tight jersey), it's the kit technician that players will turn to.
He's the one at fault should the team's kit fail to turn up at the ground, or the previous day's training kit hasn't been laundered.
For the kit technician, every training session or match produces a mountain of laundry that must all be washed, dried and allocated back to its owner.
On match days he is responsible for laying the national shirt and other kit out in the appropriate location in the changing room - observing, of course, all the superstitions players have about who changes where!
MASSEUR: When, after another hard 80 minutes of Test rugby, 15 tired players troop off the pitch, the masseur is greatly in demand.
Cramp is a particularly common complaint, so the masseur must be ready to soothe any tired limbs.
A post-match massage often reduces the chance of a player tearing or pulling a muscle in the following few days, thereby increasing their chances of being fit for the next game.
PHYSIOTHERAPIST: The sight of the physio sprinting onto the field is a familiar one.
During a match the physio has a matter of seconds to diagnose an injury, assess its severity and administer treatment.
Although many stoppages are for minor wounds, niggles or cramp, it is of paramount importance that the physio makes a correct judgement.
The sheer volume of the workload means many teams employ two or more physiotherapists.
They provide a similar service on the training pitch and often work on rehabilitation programmes for injured players away from the national squad environment.
KICKING COACH: The importance of having a good kicking coach has increased in recent years as the margins between the top sides narrow.
Now, a missed kick can frequently be the difference between winning and losing a Test match.
The kicking coach's role is to work mainly with the fly-half and/or the team's goal-kicker, refining each individual's place-kicking technique in an effort to raise the kicker's success rate as high as possible.
They will also provide tips for tactical kicking all the players, particularly the backs, showing them the best way to achieve maximum distance on a kick to touch, for example.