Joshua is a very talented fighter, I will say that he for sure is more talented than Breazeale. But the one thing that no one can discount is the heart of Breazeale. He is a person who took up fighting late and was able to go to the Olympics a few years after starting the sport. I have seen him get up off the canvas and beat an extremely determined Mansour by making him quit. Heart counts for a lot, but it's not everything. There is no denying Joshua's skill level, which is tops. The punch he knocked out Martin with came from an opportunity Joshua saw in Martins lazy jab and his not defending himself properly. Chances are this fight ends in a 2nd round KO for Joshua BUT... and it's a big but... I give Breazeale a better chance of beating Joshua than any of Joshua's previous opponents. Breazeale is the best opponent Joshua has faced, much better than the off balance amateurish Whyte. Breazeale has a strong chance at an upset... I do have questions about Joshua's chin, especially with rumors of knockdowns in sparring. SO it's 70% Joshua gets the KO and 30% Breazeale gets the upset.
Breazeale has better power and chin. Both have no footwork and basically nothing else so it will come done to these two attributes where Breazeale will prevail.
Joshua in 5, although Breazeale has fought the better opponent in Mansour I thought he looked terrible up until Mansour hurt his jaw. Not hooked on AJ but he's the best of the two.
AJ by TKO in round 6. It'll be interesting to see what kind of shape Breazeale will be in come fight night. From what I've seen on YouTube he is not as athletic as Joshua. Slow, drops the guard a lot but he knows how to box well for a late learner and a tough guy so hence my round 6 prediction.