The #2 ranked lightweight, despite being ranked a spot below Charles Oliveira, probably has the strongest case for the next crack at the 155 lb. belt ... and the UFC superstar tells us he's preparing to fight Islam Makhachev in early 2024!

"No, I haven't had any conversations yet [with the UFC about fighting Makhachev]," Gaethje told Babcock on the TMZ Sports TV show (airs weeknights on FS1), adding ... "I'm expecting to fight [Islam] February, March of next year, so that's what I'm getting ready for."

34-year-old Gaethje's coming off an impressive KO win over Dustin Poirier at UFC 291 in July 2023. Justin's now ranked 2 at lightweight, while Charles is 1, and Islam's champ.

Oliveira and Makhachev were supposed to fight in the main event at UFC 294 on Saturday, but Charles was forced to withdraw less than 2 weeks before the fight over an injury.

Justin clearly believes Charles, who previously fought and lost to Islam by submission in late 2022, has missed the bus on a title shot ... at least in the immediate future.

"Like I said, Oliveira had his chance and then he had his second chance and backed out," Gaethje said.

It's clear JG believes the fight's his, so we asked him ... how do you match up with the champion?

"With the experience I've had with Khabib, I understand that he's not the same fighter. I wasn't scared of Khabib, but that's an intimidating guy to go up against, and that factor will not be there. I'm more confident," Gaethje said, reflecting on his experience with Nurmagomedov, and how the Makhachev fight would be different.

"I think I'm a great matchup. I think it's a much better match-up for myself than Khabib was, and I think I'll be able to really be effective with my striking and then create some opportunities to maximize the damage that I'm creating."