When a football club asks an agent to find a No 7, it is apparent they looking for a winger or second striker. When they seek a No 9, it is obvious a striker is required.
Tottenham's Son Heung-Min might wear No 7, but we've now seen that the South Korean can fill the No 9 position just as well.
In Tottenham's opening Premier League game against Manchester City, without recognised centre-forward Harry Kane, manager Nuno Espirito Santo put Son in his place, and he proved he could play there much better than many specialists.
The No 7 shirt was always a symbol of a player roaming the open spaces, someone who deceives with unpredictable movements and appears in the shooting zone. Son has it all in his game, and Nuno must be delighted.
Son is not the most elegant player but he always leaves defenders trailing and, in the blink of an eye, he gains metres. He prefers to have space in front of him.
Armed with extraordinary speed and amazing dribbling ability, Son is two-footed and is fearsome on both sides of the attack. Versatile, he is able explore his pace and tricks anywhere along the frontline, including standing in for Kane.
Son has developed a fantastic partnership with Kane, and there is no doubt they must be regarded as one of the deadliest duos in the world. Now that Kane has confirmed he will stay at Tottenham, the pair will continue to be formidable.
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This South Korean landed in Hamburg in 2008 at the age of 16. After a few years he joined Bayer Leverkusen for the 2013/14 campaign, where he spent two seasons before his move to Tottenham in 2015 and has just renewed his contract until 2025.
Upon his arrival in London, Son became a fan favourite both for his skills on the field, but also for his personality and serenity and his beaming smile.
It is surprising that, in recent years, the name Son Heung-Min has rarely been linked with the biggest teams in world football.
Maybe now with his prowess proven anywhere in the attack, things will change.