Advice about a potential job-Potential involuntary reference

I applied for a job a couple weeks ago. Today, they called and left a message to call them back. The company that I work for does business with this company so I asked my boss what he knew about the company and why (he knows that I am looking). It turns out that someone who used to work in management for my current company now works for that company. He now works at a different location for that company, but until recently was their plant manager.
This person frequently interacted with me during my time at the company. My boss doesn't think that the former manager would give me a bad reference if asked. My memories of this person say otherwise. Still, this man was familiar with what I do at my current position and of course knows my company well. Although the other company is larger (but not huge) given his recent position at that plant, should I expect that they will contact this man regarding me whether I mention it or not? Should I mention, up front, that I worked with their former plant manager?
The position that I am applying for is a management position in the plant. I don't have any direct management experience, but I am very knowledgable in that specialty and work with little supervision. The mentioned manager knows that about me. He left my current company 2 years ago.

like you don't know the other guy works there.

I didn't know that he worked there when I applied for the job. I just set the interview and was given the names of the people who I will be interviewing with and he isn't one of them (not that I expected him to be since he is now at a different location). If they mention him, I'll pretend to be suprised.

There's no point starting something that doesn't have to be. If they ask, be upfront.

However, do a personal review of your relationship with this person and make notes. Try and anticipate things he might have to say about you and issues that might arise from them consulting with him about you. DO you anticipate he would be hostile or negative ?

Try and explain and resolve issues without making the guy the enemy, either then or now. Don't forget he's presumably a trusted employee of the compnay you're interested in. But also don't forget he left your current company for some reason(s).

There were a couple of issues. I suppose that even if what he says reflects badly upon me, if asked I can mention my growth as a person and professional in the past two years.
Of course, I don't know what his attitudes are about my current company or me now that a little bit of time passed. He didn't leave on the best terms, but it wasn't because of me.