ONE Championship flyweight champion Demetrious Johnson believes Alexandre Pantoja would be a very tough test.

Pantoja recently became the new UFC flyweight champion after a split decision victory over Brandon Moreno in the UFC 290 co-headliner last month.

The Brazilian is just the fourth UFC champion to hold the belt at 125 pounds following Johnson's long reign with the Las Vegas-based promotion that saw him earn a record 11 consecutive title defenses.

While they've never crossed paths before, “Mighty Mouse” believes he would have to use all of his skill set to come out on top against Pantoja in a potential fight between the two champions.

“It would be very, very tough,” Johnson told MMA Junkie Radio. “The biggest thing I think Pantoja has is very good jiu-jitsu. He’s very tough. He’s got a great chin. I think I would have to use all my skill set to beat him at that time when I was in the UFC.

“But he’s well-rounded, he hits hard, he’s dropped people, he’s knocked people out – it would have been a great fight.”

All that said, Johnson is happy to see Pantoja do well, especially given that he felt he was a dark horse in a division that was stalled with the four fights between Moreno and Deiveson Figueiredo.

“I’m always happy that any athlete succeeds – especially Pantoja. He just beat Brandon Moreno,” Johnson added. “I’ve always felt Pantoja was the dark horse in the division. A lot of times, not the best athlete gets the opportunity to shine under the big lights or under the big stage, and I was very happy for Pantoja.”

Whether a fight between the two could ever happen seems unlikely not just because of them being in different promotions — there's still a possibility Johnson never fights again.