Ricky Martin 100% seemed to have an erection at Madonna's show this past weekend -- while it may have been unclear at first ... this new video leaves nearly no doubt.

Check out this video we obtained that captures the erotic moment from Sunday's concert in Miami -- where Rick was onstage with Madge and getting a lot of close contact from her dancers during the "Vogue" segment of her show ... where she and a guest judge them.

As you can see in this footage -- shot from a much closer vantage point and at a slightly different angle -- Ricky does, in fact, appear to get aroused during the sexy rub-up.

The one dancer who's closest to Ricky seems to actually bump his face and head up against the guy's crotch -- and RM's body does a little reacting to that ... namely, a bit of throbbing and jostling underneath his pants -- that's certainly what it looks like anyway from here.

Remember ... Ricky himself posted the OG video that showed him onstage -- and at first it was unclear if he was feeling randy, or if there was just something funky going on with his pants.

It was a bit of an optical illusion ... but now, with this new POV, it's clear what was going on. Considering the guy up front was making contact with Rick -- not to mention the fact he was literally fanning himself up there -- there's almost no doubt ... RM was upside down, inside out.

One last tidbit about this that makes the whole thing all the more hilarious ... Alex Rodriguez and Chris Rock were in the crowd that night -- and we're told they caught Ricky's moment!

No word on what they thought of it ... but they were definitely paying attention, just like everyone else there that night.