Turning pro in April of 1972 at The Forum in Inglewood, CA, Chacon went on to become a firm fan favourite. A 1973 loss to Mexican great Ruben Olivares proved a setback, with Chacon losing his unbeaten record, but he bounced back and, just six fights later, including a win over an unbeaten Danny Lopez, Chacon defeated Alfredo Marcano to win the vacant WBC 126-pound title. Just one retention followed, before Chacon met Olivares in a return. Losing again via stoppage, Chacon would also lose his next but one fight – to Rafael “Bazooka” Limon.

This rivalry proved to be one of the most fierce in boxing history. Limon, yet another great Mexican warrior, fought Chacon on four occasions and each fight was brutal. The first encounter between the two was the only one Limon won, with Chacon winning two decisions and the two boxing a technical draw. In between his wars with Limon, Chacon met Olivares for a third time, this time getting a non-title points victory.

It is the battles with Limon that Chacon is most celebrated for though. In their final meeting, in 1982, Chacon won a gruelling 15-round split decision to win the WBC 130-pound crown and become a two-weight ruler. This win was especially impressive as it came after Chacon had lost two previous challenges for that title – losing to Alexis Arguello and Cornelius Boza-Edwards.

01. Chuco Castillo...........................Fight # 19

02. Ruben Olivares I.......................Fight # 20

03. Jose Luis Del Campo II...........Fight # 22

04. Danny "Little Red" Lopez.......Fight # 25

05. Alfredo Marcano.......................Fight # 26

06. Ruben Olivares II......................Fight # 28

07. Miguel Meza...............................Fight # 35

08. Miguel Estrada..........................Fight # 38

09. Augie Pantellas..........................Fight # 43

10. Rafael "Bazooka" Limon II........Fight # 46

11. Alexis Arguello.............................Fight # 48

12. Rafael "Bazooka" Limon III.......Fight # 49

13. Cornelius Boza Edwards I.........Fight # 52

14. Rafael "Bazooka" Limon IV.......Fight # 58

15. Cornelius Boza Edwards II........Fight # 59

16. Ray "Boom Boom" Mancini.......Fight # 60

17. Davie Montana.............................Fight # 63

18. Arturo Frias...................................Fight # 64

19. Rafael Solis...................................Fight # 65

20. Bobby Jones...............................Fight # 66