The British fighters will go head-to-head in a heavyweight world title fight at Wembley Stadium next weekend and the promoter thinks his charge could end the hopes of the former world champion with a convincing victory.
Warren told Sky Sports News: "It's how you lose a fight. If he lost the fight convincingly, it would be hard for him to come back if he wanted to carry on.
"But he could lose a close fight or by a debatable decision. Anything can happen in boxing."
The promoter thinks that Joshua is under more "pressure" heading into the fight as he is a more recognisable figure for fans of the sport than Dubois – who inherited the IBF title belt when it was vacated by Oleksandr Usyk.
Warren said: "The pressure is on AJ. He's the bookmaker's favourite, the fans' favourite, and obviously the better-known boxer of the two, certainly in the UK. Everything is on him."
The promoter is convinced that his fighter has what it takes to pull off the win despite his lack of experience in high-pressure bouts compared to Joshua.
He said: "These are two British guys on a roll, coming off some good wins, although I believe Daniel's opponents have been superior and better quality than AJ's.
"AJ's got more of the experience but there comes a time in boxing when it's a young man's game. I believe this young man (Dubois) is on his game at the moment and I do think he'll come away as the victor."