Claressa Shields calling out Amanda Nunes for a boxing bout and mixed martial arts match definitely caught the attention of Heather Hardy and Amanda Serrano.As it should have, considering the veteran boxers have already crossed over to MMA and spent the last couple of years segueing between the two sports. So they, more than most, know what Shields would have to endure to step foot into the cage for an MMA match. There was a time Serrano offered to spar with former UFC sensation Ronda Rousey in boxing, though it never came to fruition. So, it will be tough to strike a two-fight deal pitting Shields vs. Nunes in the ring and Octagon. (It was also tough to make the Floyd Mayweather Jr.-Conor McGregor boxing bout in August 2017, and that made history).In the meantime, Shields is slated to face Ivana Habazin on Oct. 5 for the vacant WBO women’s junior middleweight title with the chance to become the quickest three-division world champion in boxing history. That’s first in line for the self-proclaimed “Greatest Woman of All Time (GWOAT).”But if Shields vs. Nunes actually happens, there’s no doubt Hardy and Serrano — and the combat sports world — will be watching keenly. On Tuesday, Hardy and Serrano formally announced their own fight for Sept. 13 at the Hulu Theater at Madison Square Garden, live on DAZN. So Sporting News asked them to share their thoughts about a pair of possible Shields-Nunes super bouts.Join DAZN and watch Hardy vs. Serrano on Sept. 13Both Brooklyn fighters believe Shields would take the boxing bout. Serrano, the only seven-division women’s world champion in boxing history, even cautioned to combat sports fans not to sleep on Shields’ ability to win the MMA match as well.“Claressa Shields is a big, tough woman and my hat goes off to her,” Serrano said. “MMA is a total different sport, but she’s a hard worker. She’s determined, so whatever she puts her mind to, I know she’s going to do good in it.“Amanda Nunes is a veteran in the sport, but if Claressa Shields can catch her a couple of times, it’s not going to be the same outcome,” she continued. “But it’s hard because in MMA there’s so many different arts. But I know Claressa is going to give it her all.”Hardy agreed, also noting the adjustment from boxing to MMA will be hard because the latter sport is more “technical.” However, the WBO featherweight champion sees the potential super clashes as a huge opportunity for Shields — the undisputed women’s world middleweight champion — to rake in a deluge of new fans for herself and for women’s boxing.“That would be great for boxing,” Hardy said of a pair of fights between Shields and Nunes.MORE: Hardy, Serrano say time is right for fight“That’s part of why I went over to MMA — to take some of the fans because there were so many more fans in women’s MMA. So, to be able to expose some of Amanda’s millions of fans to women’s boxing and Claressa and the talent pool that’s here … that’d be incredible.”Hardy and Serrano enter their fight for Hardy’s featherweight title next month each coming off an MMA bout. Hardy was thoroughly dominated by Taylor Turner via a first-round TKO (punches) at Bellator 222 back in June, bringing her MMA record to 2-2.That’s compared to her 22-0 record, including 4 KOs, in boxing.Meanwhile, Serrano fought to a draw in her first MMA fight and won her second bout via a first-round submission (rear naked choke) against Eréndira Ordoñez — both in Combate Americas.After scoring a first-round TKO of Eva Voraberger in January to become a seven-division world champion, Serrano (36-1-1, 27 KOs in boxing) participated in her second jiu jitsu tournament and scored a win in her only bout in February.