Claressa Shields Targeting MMA Fight in 2020, Kayla Harrison Offers to Train!

Boxing superstar Claressa Shields is getting more and more serious about switching over to MMA -- telling TMZ Sports she's down to fight in 2020 ... and she's getting help from one of the BEST in the game.

Shields is 9-0 as a pro boxer and holds a BUNCH of world titles -- but she admits she's getting a little bored with the lackluster competition in women's boxing ... and wants a challenge.

Shields recently began training in MMA with accomplished wrestler Adeline Gray -- and she's doing really well.

In fact, MMA rising superstar Kayla Harrison was so impressed ... she's offered to step in and help Claressa too.

"I see some true potential there," Harrison says ... "If she wants to continue to work on her [double leg takedown], she's got my number. I'll show her some judo throws. We can make it happen!"

Harrison told Shields there's one catch ...

"As long as you help me straighten out my striking! So far in my MMA career, I've thrown about zero punches on my feet."

Kayla thinks Shields could take a pro-MMA fight in 6 months -- and when we asked Shields if that sounded realistic, she was all about it.

"Yeah! It sounds great! MMA is interesting because I just love fighting, I really do. I love to punch people!"

Ultimately, seems Claressa's goal is to fight UFC superstar Amanda Nunes -- which would be AWESOME!!!