Liston and patterson would give him problems but i'm not completely sold on him losing those fights handily. Patterson was annihilated by liston twice, so a power puncher that just keeps coming would have a good shot at beating patterson. Liston would be arguably the toughest fights of rocky's career and when you throw in his age by then, it doesn't look good but it wouldn't be impossible. Now fighting some guy named Cassius Clay around the time rock was approaching 40, is completely ill-advised.