Lewis has said before that when he sparred with a young Tyson he thought "I don't wanna run into this guy in the ring, he's an animal". Tyson did have problems with good boxers even in his prime but at worst he would win on points or stop them in the middle rounds. It'd be hard for Lennox to land regularly on Mike with all the offense and headmovement. Not to mention he would not give Lennox space to get leverage on his shots. I think Mike would eventually overwhelm Lennox and probably stop him around the 7th. But if somehow Lennox could get past the 7th or 8th and keep it in the middle of the ring, he too could win the fight.