Former women's boxing champion Holly Holm, who retired from the sport in 2013 to pursue a full-time career in mixed martial arts, says the upcoming bout between Floyd Mayweather Jr. and Conor McGregor is a real fight.

Holm, who left boxing with a record of 32-2-3, 9 KOs and recognition as one of the best women fighters in the sport, made a huge name for herself in MMA after a stunning upset knockout of Ronda Rousey, who many felt was unstoppable at the time. Holm drilled Rousey in two rounds in 2015 to capture the UFC championship.

Now two-division UFC champion McGregor, regarded as one of the best MMA fighters in the world, will attempt to pull off a shocker of his own when he faces Mayweather on August 26th at the T-Mobile Arena in Las Vegas.

Holm, one of the few fighters to find success in both boxing and the UFC, believes Mayweather-McGregor is far from a black eye to boxing and also doesn't rule out the possibility of a McGregor upset.

For McGregor, this will be his first pro boxing match. Mayweather, 40, is coming back from a two year retirement - and is viewed as a massive favorite to win. The two fighters will wear 10 ounce gloves at the junior middleweight limit of 154.

According to Holm, there are far less fighting habits to break when going from MMA to boxing than going from boxing to MMA.

She says the critics who are abusing the contest have never actually fought themselves.

“If McGregor wins, its going to be earlier,” Holm said to MMA Fighting. “If it goes longer, it’s going to be Floyd Mayweather. Anything can happen in a fight. I don’t think it’s a disgrace. I think if anyone’s out there making fun of this fight, I can guarantee you that those are the people who don’t fight.”

“I think one of the biggest thing for me going from boxing to MMA that was hard was being close in the clinch, because in boxing I could get comfortable in there. You could cover up and throw uppercuts and hooks and call it phone booth fighting and when I first got into MMA, sometimes I’d want to stand in there and throw uppercuts and then all of a sudden they’ve got me in the clinch. Or, I’m trying to box and somebody would go for a takedown.”

“So one of the biggest habits I had to break going into MMA was letting go of that inside boxing style, which I didn’t do all the time but I was comfortable there in the fight and I feel like, going from MMA to boxing, is, I don’t want to say an easier transition, but I just feel like, there aren’t a lot of habits you’d have to break.”