10. Michael Essien (Lyon)
Value in 2004: €12m
Highest career value: €38m
What. A. Player. Following his brilliant displays out in France, Chelsea splashed the cash on the Ghanian in 2005 and the Blues reaped the rewards instantly.
One of the greatest defensive midfielders of all-time - who also impressed on-loan at Real Madrid 2012/13 - left Chelsea in 2014 and is still playing out in Azerbaijan with Sabail.
Grade: 9/10
9. Andres Iniesta (Barcelona)
Value in 2004: €12m
Highest career value: €70m
He turned out okay, didn't he? Back in 2004, the Barcelona legend was a raw La Masia graduate making his way in the world of football.
Pretty soon after, the Spaniard had developed into one of the greatest midfielders of all-time and the Blaugrana are still struggling to find a suitable heir for the little magician.
Grade: 10/10
8. Daniele De Rossi (AS Roma)
Value in 2004: €14m
Highest career value: €38m
One of the most underrated players since the turn of the millennium.
A World Cup-winner with Italy in 2006 and a quality, loyal servant to Roma, De Rossi called time on his career in January after a short spell with Boca Juniors.
Grade: 8/10
7. Carlos Tevez (Boca Juniors)
Value in 2004: €15m
Highest career value: €40m
After lighting up Argentinian and Brazilian football, Tevez swapped South America for England in 2006 and flourished with West Ham, Man United and Man City.
He was also immense during his two years with Juventus, before THAT move to China in 2015. Tevez is now back with Boca and he's still finding the back of the net regularly.
Grade: 8/10
6. Cristiano Ronaldo (Man Utd)
Value in 2004: €18m
Highest career value: €120m
We don't really need to say much here, do we?
From exciting youngster in 2004 to possibly the greatest footballer of all-time in 2020. What a journey it has been for Ronaldo.
Grade: 10/10 (maybe even 11!)
5. Arjen Robben (Chelsea)
Value in 2004: €20m
Highest career value: €40m
Robben was very good at Chelsea and - to a lesser extent - with Real Madrid, but it was with Bayern Munich where he cemented his legacy as one of the greatest wingers of all-time.
Imagine how good the Dutchman - who is still a free agent - would have been had it not been for persistent injuries?!
Grade: 9/10
4. Robinho (Santos)
Value in 2004: €22m
Highest career value: €36.5m
So much was expected of the Brazilian, who was viewed by many as the heir to Pele's throne back in 2004.
His above average spell at Real Madrid was followed up by a pretty disastrous stint with Man City. Afterwards, aside from a few glimpses of quality at AC Milan, Robinho's career has never really recovered. The 36-year-old is now in Turkey with Istanbul Basaksehir.
Grade: 5/10
3. Fernando Torres (Atletico Madrid)
Value in 2004: €25m
Highest career value: €50m
For a time, Torres was the best striker in the world at Liverpool and with Spain. You just couldn't stop him, he was too quick and - above all - too good.
But he couldn't preserve his place at the top for quite long enough, with his £50m move to Chelsea derailing the latter stages of his career. However, Torres will always be both an Atletico Madrid and Liverpool legend.
Grade: 8/10
2. Jose Antonio Reyes (Arsenal)
Value in 2004: €35m
Highest career value: €35m
Reyes hit the ground running upon his move to Arsenal in 2004, but his career in England quickly petered out.
Spells at Real Madrid, Atletico Madrid, Benfica, Sevilla and Espanyol followed, but Reyes just couldn't rediscover the form he had shown in '04.
Grade: 6/10
1. Wayne Rooney (Man Utd)
Value in 2004: €37m
Highest career value: €65m
Manchester United and England's record goal scorer, a five-time Premier League and winner and - to put it simply - one of the greatest players English football has ever seen.
The hype surrounding Rooney in 2004 was enormous, but it really was more than justified.
Grade: 10/10
Aside from Robinho, the entire top 10 have earned ratings of 6/10 or higher, which is testament to the wealth of young talent that was on show back in 2004.