Marcelo exerts an assertive passing attack from standing against an Open-Guard: If your opponent is seated, sitting upright on the ground playing an empty Butterfly-Guard (a.k.a. Sitting-Guard, Seated-Guard, et al.), they may be poised to wrestle-up onto a Single or into a Double-Leg Sweep if you engage precariously; similarly, if you wade forward into their guard without an attack, they may drop back into any number of supine-guard variations, e.g. De-la-Riva, Reverse-DLR, etc. Alternatively, one can enter in on their own terms by stepping deep in between the opponent's leg's, wedging their knee up the middle, and shoving them back flat on the mat before they can meaningful attach any offensive control. Use your palm to press down onto their torso to help pin them in place as you work to bring your trailing-leg outside of their legs, forcing them into an R-Guard (a.k.a. Reverse-Guard, Headquarters, Open-Half, Standing-Half, et al.). Once your leg is posting on the outside, swing your inside-leg high and backwards, effectively pulling it out from in between their guard while also pressing down on the top of their knee with your other hand. Before your opponent has a chance to make an adjustment towards recovery, bring your knee fast and hard back down on top of your opponent's torso, replacing your posting-hand for Knee-on-Belly (Knee-Mount, Knee-Ride, Knee-in-Stomach, Ukigatame, et al.). Follow your opponent's subsequent attempts to hip-escape by riding or floating above them with your shin-across until you notice an opportunity to lower your level down into chest-on-chest connection, secured with an Under-Hook & Head-Control. Remember to consolidate on top by conservatively arriving with your hip-weight remaining well in front of their center-line as you tighten down.