Diego Costa is officially a free agent.

On Tuesday, Atletico Madrid announced that they had terminated the Spaniard's contract six months before its expiration.

The 32-year-old striker is now free to sign for any club in world football and he's already been linked with a switch to Premier League giants Arsenal.

Fans of the north London club are, understandably, not overly excited about the prospect of signing Costa, but the former Chelsea man is the most valuable free agent available right now.

In fact, he's the most valuable by a considerable distance.

Costa in action with Atletico

Transfermarkt have provided the figures for the 20 most valuable free agents in world football going into 2021 and some blasts from the past feature in the list.

Let's take a look...

20. Yaya Sanogo

Age: 27

Market value: €2m

19. Wilfrid Kaptoum

Age: 24

Market value: €2m

18. Nathaniel Mendez-Laing

Age: 28

Market value: €2.2m

17. Jozo Simunovic

Age: 26

Market value: €2.2m

16. Mario Mandzukic

Age: 34

Market value: €2.4m

Mandzukic with Juventus

15. Bruno Uvini

Age: 29

Market value: €2.4m

14. Ezequiel Garay

Age: 34

Market value: €2.5m

13. Oumar Niasse

Age: 30

Market value: €2.5m

12. Jackson Irvine

Age: 27

Market value: €2.5m

11. Kevin Stewart

Age: 27

Market value: €2.8m

Stewart with Hull

10. Daryl Janmaat

Age: 31

Market value: €3m

9. Jese Rodriguez

Age: 27

Market value: €3m

8. Wilfried Bony

Age: 31

Market value: €3.2m

7. Ramires

Age: 33

Market value: €3.5m

6. Alexandre Pato

Age: 31

Market value: €3.5m

Pato with Sao Paolo

5. Kwadwo Asamoah

Age: 32

Market value: €4m

4. Daniel Sturridge

Age: 31

Market value: €4m

3. Jack Wilshere

Age: 28

Market value: €4m

2. Ahmed Musa

Age: 28

Market value: €6m

1. Diego Costa

Age: 32

Market value: €10m

Costa with Atletico

Costa is currently valued at €10m, €4m more than former Leicester City striker Musa in second place.

Sturridge and Wilshere sit behind the two frontrunners and it seems odd that an English club hasn't taken a punt on either player as of yet.

Both have had considerable issues with injury in recent years, but could still have a lot to offer a team in either the Premier League or Championship if they get back to full fitness.

Lest we forget, Sturridge and Wilshere were brilliant at Liverpool and Arsenal in their respective heydays.