Olympian Kayla Harrison Gets MMA Help from Ronda Rousey

Olympic judo superstar Kayla Harrison says Ronda Rousey has given her "a lot of help" when it comes to making the transition into MMA -- but the real question ... would she ever take a fight against her old friend?

TMZ Sports spoke with 26-year-old Harrison -- a 2-time Olympic gold medalist in judo -- who says she trained with Rousey every day for 7 years as they fought their way to the top of the sport.

Now, with Harrison signing a contract with the World Series of Fighting -- she says she'll reflect on the advice she got from her old friend as she begins her training.