Throughout the course of a year, a player's market value is at risk of decreasing.
Age is usually the key factor in this regard, although poor form out on the pitch or a prolonged spell on the sidelines can both play a significant role as well.
The year of 2021 has seen a high number of big-name players' values decrease, with Lionel Messi, Neymar and Kylian Mbappe all featuring in the top 25.
There are also a few younger footballers on the list, most notably Joao Felix and Ansu Fati.
But which player's value has decreased the most since January 1st over on Transfermarkt? Well, you can find out the answer to that very question below.
Let's begin...
25. Thiago Alcantara (Liverpool) | -£16.20m
Market value: £27.00m
Percentage decrease: 37.5%
24. Moussa Dembele (Lyon) | -£18.00m
Market value: £18.00m
Percentage decrease: 50%
23. Eden Hazard (Real Madrid) | -£18.00m
Market value: £36.00m
Percentage decrease: 33.3%
22. Paulo Dybala (Juventus) | -£18.00m
Market value: £45.00m
Percentage decrease: 28.6%
21. Antoine Griezmann (Barcelona) | -£18.00m
Market value: £54.00m
Percentage decrease: 25%
20. Ansu Fati (Barcelona) | -£18.00m
Market value: £54.00m
Percentage decrease: 25%
19. Alisson Becker (Liverpool) | -£18.00m
Market value: £54.00m
Percentage decrease: 25%
18. Serge Gnabry (Bayern Munich) | -£18.00m
Market value: £63.00m
Percentage decrease: 22.2%
17. Jan Oblak (Atletico Madrid) | -£18.00m
Market value: £63.00m
Percentage decrease: 22.2%
16. Joao Felix (Atletico Madrid) | -£18.00m
Market value: £72.00m
Percentage decrease: 20%
15. Lionel Messi (Paris Saint-Germain) | -£18.00m
Market value: £72.00m
Percentage decrease: 20%
14. Raheem Sterling (Manchester City) | -£18.00m
Market value: £81.00m
Percentage decrease: 18.2%
13. Mohamed Salah (Liverpool) | -£18.00m
Market value: £90.00m
Percentage decrease: 16.7%
12. Kevin De Bruyne (Manchester City) | -£18.00m
Market value: £90.00m
Percentage decrease: 16.7%
11. Kylian Mbappe (Paris Saint-Germain) | -£18.00m
Market value: £144.00m
Percentage decrease: 11.1%
10. Roberto Firmino (Liverpool) | -£19.80m
Market value: £45.00m
Percentage decrease: 30.6%
9. Renan Lodi (Atletico Madrid) | -£22.50m
Market value: £22.50m
Percentage decrease: 50%
8. Clement Lenglet (Barcelona) | -£22.50m
Market value: £22.50m
Percentage decrease: 50%
7. Virgil van Dijk (Liverpool) | -£22.50m
Market value: £49.50m
Percentage decrease: 31.3%
6. Neymar (Paris Saint-Germain) | -£25.20m
Market value: £90.00m
Percentage decrease: 21.9%
5. Miralem Pjanic (Barcelona) | -£27.00m
Market value: £18.00m
Percentage decrease: 60%
4. Philippe Coutinho (Barcelona) | -£27.00m
Market value: £27.00m
Percentage decrease: 50%
3. Saul Niguez (Atletico Madrid) | -£27.00m
Market value: £36.00m
Percentage decrease: 42.9%
2. Trent Alexander-Arnold (Liverpool) | -£31.50m
Market value: £67.50m
Percentage decrease: 31.8%
1. Sadio Mane (Liverpool) | -£31.50m
Market value: £76.50m
Percentage decrease: 29.2%
Champions League 2021/22: Fixtures, Draw, Results, Odds, Scores And Everything You Need To Know
Both Mane and Alexander-Arnold have seen their values decrease by £31.50m in the space of around eight months.
The pair are two of seven Liverpool players in the 25-man list above, making the Reds the unfortunate team with the most representatives.
That's sadly the price you pay for going from Premier League title winners to scrapping for Champions League football...