Tradition dictates that centre-forwards must wear the Number 9 jersey and the number is usually reserved for a particular type of striker.
The Number 9 generally playsahead of the Number 10 in an advanced forward role, occupying centre-backs and getting onto the end of crosses or latching onto through balls in behind the defence.
Generational talents and tactical innovations have seen the odd alteration to the style of the Number 9, but the job remains the same: bring your team-mates into the game and score goals.
Goal takes a look at some of the best Number 9 strikers in football...
Alan Shearer | England
An intelligent andtough operator, Alan Shearer is one of England's greatest ever strikers and was renowned for his heading ability. He is, by some distance, the best goalscorer in Premier League history with 260 goals in 441 appearances and struck 30 goals in 63 games for England.
Ronaldo | Brazil
Known as 'The Phenomenon' in Brazil, Ronaldo is widely regarded as one of the best Number 9s ever to grace a football pitch. Tall, strong and possessing lightning pace, Ronaldo dazzled defenders while playing for the likes of Barcelona, Inter and Real Madrid. The Brazilian sensation's arrival in the 1990s marked a noticeable evolution in the role of the Number 9, bringing more dynamism and panache. He scored over 400 goals in his career, including 62 for his country.
Gabriel Batistuta | Argentina
Gabriel Batistuta's exploits leading the forward line earned him the nickname 'Gabigol' and he was undoubtedly one of the finest Number 9s of his generation. A fearsome competitor, Batistuta could score goals in any fashion, whether it was a ferocious effort from the edge of the box or a deft front-post header - he could do it all.
Robert Lewandowski | Poland
Poland's greatest goalscorer of all time, Robert Lewandowski emerged as one of the best strikers in the world while playing for Jurgen Klopp's Borussia Dortmund and his subsequent exploits at Bayern Munich cemented that reputation. The spearhead of the attack, Lewandowski's pace, power and technique are crucial tools in his style of play.
George Weah | Liberia
Like Ronaldo, George Weah was among a crop of strikers who revolutionised the Number 9 role in the 1990s, bringing greater emphasis on skill and speed. Weah won the Ballon d'Or in 1995 and is regarded as one of the greatest African footballers of all time thanks to his performances for AC Milan, Paris Saint-Germain and Monaco, as well as Liberia.
Harry Kane | England
The role of strikers has changed ever since the emergence of the 'False 9', but Harry Kaneis a reminder that there is still a place for the classic out-and-out striker so long as the system suits. Frequently described as 'old fashioned' in his playing style, Kane is one of the most prolific attackers in the world. He has already surpassed Alan Shearer's tally for England - doing so in fewer games - and is one of the all-time top 10 goalscorers in Premier League history.
Marco van Basten | Netherlands
Marco van Basten was one of the best strikers in the world during the 1980s, shining for Ajax and the Netherlands. He was the focal point of the Dutch side that won Euro 88 and his style of play earned him the nickname 'The Swan of Utrecht'. Van Basten scored 24 goals in 58 caps for the Netherlands and won the Ballon d'Or on three occasions.
Zlatan Ibrahimovic | Sweden
Standing at 6'4", Zlatan Ibrahimovic could have been forgiven for relying on his sheer physicality during his career, but the towering Swede has no shortage of technical ability either and that is what distinguishes him. Ibrahimovic's versatility has seen him deployed as a second striker and even as a Number 10, but he excelled as a Number 9 in the early stages of his career.
Ruud van Nistelrooy | Netherlands
Ruud van Nistelrooy actually began his career as a Number 10, but he transformed into one of the best out-and-out strikers in the world, starring for PSV, Manchester United and Real Madrid as well as internationally for the Netherlands. His tall frame meant that he was an ideal target man and his technical ability allowed him tobring his team-mates into the game in the final third.
Karim Benzema | France
Were it not for Cristiano Ronaldo, Karim Benzema would have a few more individual awards for goalscoring in his trophy cabinet. The former France international is a legend at Real Madrid, where he has become one of the best strikers in the club's history. Benzema's power and agility were key skills in his locker when he broke through at Lyon, and he has seen off plenty of competition at Madrid.
Gerd Muller | Germany
'Der Bomber' Gerd Muller is widely regarded as one of the most clinical strikers of all time and his tally for West Germany - 68 goals in 62 games - exemplifies that fact. Muller was the focal point of the German attack and that of Bayern Munich, using his impressive core strength and elusive agility to bamboozle defenders.
Christian Vieri | Italy
Inter legend Christian Vieri was one of the world's best strikers during the 2000s and is fondly remembered as one of the best goalscorers in Italian football history. A powerful and combative centre-forward, he was nicknamed 'The Bull' and scored 23 times in 49 caps for the Azzurri. Vieri's strength allowed him to compete with some of the toughest defenders in world football andhe was particularlyadept in the air.
Miroslav Klose | Germany
When MiroslavKlose brought the curtain down on his career in 2016, he did so as Germany's record goalscorer (71 goals in 137 games) and remains the top scorer in World Cup history with 16 goals overall, beating the likes of Ronaldo and Gerd Muller.
Fernando Torres | Spain
A legend at Liverpool and Atletico Madrid, Fernando Torres was one of the most feared strikers in the world during his prime years. His explosive pace was undoubtedly his biggest asset, but he also boasted tremendous strength, which helped him contend with the close attentions of defenders such as Nemanja Vidic, John Terry and others during his time in the Premier League.
Ian Rush | Wales
When it comes to goals scored for Liverpool, no player comes remotely close to Ian Rush,who was undoubtedly one of the best strikers of his generation. Rush hit the back of the net 346 times for the Reds and was the ideal partner for Kenny Dalglish in the 1980s.
Didier Drogba | Ivory Coast
A key component of Jose Mourinho's all-conquering Chelsea side, Didier Drogba was a nightmarish prospect for defenders thanks to his strength and tenacity. The Blues won four Premier League titles, four FA Cups and the Champions League during Drogba's time at the club and he played a crucial role.
Sergio Aguero | Argentina
Sergio Aguero is one of the most complete strikers of his generation and has become a legendary figure at Manchester City. While he excelled as a second striker at Atletico Madrid, complementing Diego Forlan, Aguero has matured into one of the best out-and-out forwards in Premier League history.
Romario | Brazil
Romario is one of the greatest goalscorers of all time and he was able to thrive as a centre-forward despite his relatively short stature thanks to his pace, movement and finishing ability. The former Barcelona and Vasco da Gama star scored 55 goals in 70 caps for Brazil.
Hernan Crespo | Argentina
An iconic figure at Parma and Lazio, Hernan Crespo was among a clutch of star Number 9s during the late 1990s into the 2000s. Strong, skilful and extremely quick, Crespo had a penchant for scoring spectacular goals. Similar in many ways to his compatriot Gabriel Batistuta, Crespois one of Argentina's greatest goalscorers.
Luis Suarez | Uruguay
Two-time European Golden Shoe winner Luis Suarez is arguably the most complete modern-day striker, having shown remarkable adaptability throughout his career at Ajax, Liverpool and Barcelona. Tenacious and driven, Suarez is third on the list of Barcelona's all-time top goalscorers and is Uruguay's record scorer.
