Shirt numbers were brought into football in 1928, to make the indication of positions easier.
However, they have evolved to become iconic symbols of football legends past and present, and the mere sight of the digits on the shirt can are enough to raise the hairs on the back of your neck.
They have been used to differentiate between legends – R9 for Ronaldo and CR7 for Cristiano Ronaldo.
They have been retired to commemorate legends from Bobby Moore’s legendary No.6 at West Ham, to Jude Bellingham’s number No.22 at Birmingham City.
However, for Chelsea’s Champions League winner Kai Havertz, his number is particularly special.
Whilst the No.29 is not a common number for star players and club record signings, Havertz explained why it has special meaning in an interview with The Athletic.
“When I was young I always used to play FIFA or Pro Evolution Soccer with my brother,” he said.
“We always made ourselves in the game. My brother always put No 29 on his shirt.
“When I came to the professional game and Leverkusen asked me what number I wanted to have, I asked them which numbers were free. When they said 29, I said I’d take it because of my brother.
“Sometimes it’s lucky for me, sometimes not, but I like the number and now I think everybody knows me for it.”
The entire Manchester City defence probably shiver at the sight of the No.29.
Afterall, it would have been the last thing they saw before the young German star bounded past their back four like a Gazelle, and rounded Ederson to score the goal that won the Champions League for Chelsea.
That one moment of brilliance has arguably enshrined the 22-year-old as a Chelsea legend, but the previous occupant of the number did not enjoy the same luck.
Alvaro Morata swapped his original No.9 shirt at Chelsea and went for the No.29 shirt.
Unfortunately, his fortunes did not change, as the Spaniard was soon sent on loan to Atletico Madrid.
Havertz faced similar struggles but finished last season very strongly for the Blues.