Ah, the number six. To some, a domineering centre half, but to many, a central midfielder with the quiet ability to dictate the tempo of his team.
Like a conductor instructing his orchestra, a good number six can take control, sometimes without fans even realising.
You can read RealSport’s best number sevens feature HERE.
The best teams in the world all have one, and only now are they starting to get the recognition they deserve.
Here are the five that are going to have a big impact in Russia.
1 Thiago Alcantara [Spain]
It feels remarkable that at the age of 27, Thiago has played just 26 minutes of senior tournament football.
He has had stiff competition, but ill-timed injuries have limited his tournament opportunities, with 15 of his 27 caps coming in friendlies.
With the likes of Cesc Fabregas and Xavi now out of the way, and finally being fully fit, the Bayern Munich midfielder will have the opportunity to assume his role as Xavi's heir in the Spain midfield.
KEY STAT: Injury limited Thiago to just 23 Bundesliga appearances in his first two seasons, compared to 73 in the last three.
Arguably as close to the perfect modern number six as is possible to find, Thiago is now such an important player for his country.
He is so skilful with the ball at his feet, an excellent passer. The Bayern man is able to look after the ball so well, even when taking risks like a low percentage final ball or taking a man on.
Alongside Koke and the evergreen Sergio Busquets, Thiago headlines a magnificent modern incarnation of Spain's legendary midfield.
His performances at the heart of his team are a big reason for Spain being fancied by many to go very far this summer.
2 Fernandinho [Brazil]
There's a major caveat to Fernandinho's inclusion - he probably won't start.
This would normally rule a player out from this series, but Fernandinho is too good a number six to not include on this list.
With Tite instead normally opting for a number four in Casemiro and two number eights in Paulinho and Renato Augusto, it looks like Fernandinho will have to make do with a place on the bench.
KEY STAT: Fernandinho completed 2,975 passes in the Premier League in 2017/1. Only Granit Xhaka and Nicolas Otamendi completed more.
He has been one of the first names on the team sheet for Manchester City this year, posting excellent numbers for interceptions and tackles made, as well as registering the third highest number of passes in the Premier League, an eye-watering 2,975.
The metronome in the middle for Manchester City, it would seem a shame if Fernandinho is to be marginalised by Brazil this summer.
But is he one of the five best number sixes going to the tournament? Absolutely.
3 Luka Modric [Croatia]
On the back of his fourth Champions League triumph, this summer Luka Modric will head to his sixth major tournament.
Considered by many to be the best midfielder in the world for a number of years now, 32-year-old Modric will be under pressure to deliver for his country as he starts to near the end of his prime.
KEY STAT: The Champions League in May was the 11th major trophy Luka Modric has won at Real Madrid.
On trial for perjury back in Croatia for allegations involving his testimony in the case of Zdravko Mamic, his popularity back home has been dented. Good performances this summer can help mend this severed relationship.
We've all seen Modric at his best, even dating back to his days at Tottenham. Impossible to dispossess, a brilliant dribbler with an amazing passing range, he has the ability to force Nigeria and Iceland to dance his tune this summer.
As for their possible group decider against Argentina, despite all wealth of attacking talent Croatia will have to face, they would back Modric and Rakitic to win a midfield battle against the likes of Ever Banega and Javier Mascherano.
4 Toni Kroos [Germany]
Next up is Modric's Real Madrid partner Toni Kroos. With those two in the midfield, it is easy to see why Real Madrid have won three consecutive Champions Leagues.
Kroos possesses absolutely wonderful technique, with the passing range and shooting ability to match.
KEY STAT: At just 28, Kroos has won a staggering 23 major trophies for Real Madrid, Bayern Munich and Germany.
The 28-year-old pulls the strings for both club and country, and is a huge part of how Germany strangle their opponents when it comes to tournament football. Suffocating them with the likes of Kroos' intelligent passing forcing them to spend a lot of time chasing after the ball.
After featuring four times from the bench as a 20-year-old in South Africa back in 2010, Kroos played every minute in 2014 on the way to Germany becoming world champions.
The Real Madrid man should start alongside the similarly experienced Sami Khedira, and with that kind of nous in midfield, Germany will be hard to stop.
5 Idrissa Gueye [Senegal]
A little bit of a wildcard pick perhaps compared to the others on this list, but Idrissa Gueye has had another quietly outstanding season at Everton.
He is so adept at winning the ball back, with brilliant stats for interceptions and tackles this season.
KEY STAT: Only Wilfred Ndidi made more tackles (138) in the Premier League in 2017/18 than Gueye (117).
Alongside Wolves' Alfred N'Diaye, Gueye will be extremely important if Senegal are to get through their group ahead of two of Colombia, Japan and Poland.
Has been gaining fans for his Everton performances, but the extent of his quality is still fairly under the radar. This could change this summer if he can transfer his club form to the World Cup stage.
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