What are some things you could do if you suspect another developer has left a poor review of your app on purpose?

Some background: I opened the google play dev console this morning and noticed that there was a new rating on my app. ( I don't get a ton of them but they're usually around 4-5 stars for this specific app )

So when I noticed that it was a 1 star rating with a somewhat angry sounding comment and a link to another competing app, I was a little concerned, but I thought perhaps there was a bug I wasn't aware of. So I began checking into the person that had left the comment, to maybe get in touch and see if it was in-fact a bug.

I opened the google plus profile associated with the comment I noticed it was full of posts for apps from the company that made the app the user had suggested, and a link to the website of the company in question.

Long story short, Although the name of the account on the comment is not the company I have a high level of suspicion that this person has put this rating to send traffic to their app instead.

What sorts of things could I do? I think android play store has a spam button, should I respond to the comment? Maybe contact the "developer" through email? I'm not sure I could be 100% certain to actually accuse them of doing this, so what might be the best course of action?