Charles Oliveira is currently without a fight at UFC Rio de Janeiro, with Rafael Fiziev forced out by an injury. However, 'do Bronx' appears concerned at the possibility of facing Mateusz Gamrot as a replacement.Ever since news of the injury broke, 'Gamer' had offered to step in as a replacement. With the Polish native's online jibes intensifying, the Brazilian addressed his concerns surrounding such a match-up.Speaking to Laerte Viana in a recent interview, the former lightweight champion admitted that a potential switch-up to Gamrot would be hard, citing the difference in fight styles between Fiziev and 'Gamer':"I was focused on a guy who comes from a striking background... with two weeks left until the fight, I have to change my whole game plan. It's very complicated... I don't want to be taken off the card. I asked for this card, I've been training like crazy for it, but in reality, you have to understand, if they offer me a guy nobody knows, how am I supposed to fight a match like that?"Oliveira added:"[Gamrot] is a good matchup for me in a sense because he's a wrestler/grappler. But it's completely different from the style I've been training for the last month or two. It's about understanding and game-planning."Check out Charles Oliveira's comments on a potential Mateusz Gamrot match-up below:Suffice it to say, 'do Bronx's' concerns didn't go unnoticed. Later in the day, Gamrot took to X to slam the Brazilian for his remarks.Mateusz Gamrot slammes Charles Oliveira over his reluctance to face himCharles Oliveira's interview with Laerte Viana seems to have riled up Mateusz Gamrot, who hopes to replace Rafael Fiziev against 'do Bronx' at UFC Rio de Janeiro.As Oliveira voiced concerns about facing 'Gamer', citing he had been preparing for a striker rather than someone with a wrestling background, Gamrot hit back at the former light-weight kingpin, writing:"I hear you’re worried about my style, even though you had a full training camp. I had none, and still I’m ready to step into the cage. Two weeks left to prepare– and I’m already in ATT right here. No excuses, let’s do this. @CharlesDoBronxs @ufc"