Play video content EXCLUSIVE TMZ.com

Mayor Pete Buttigieg isn't fooling himself ... Donald Trump will target him with homophobic remarks as the 2020 Presidential campaign heats up.

The openly gay South Bend Mayor, who has soared in popularity, will appear on "TMZ Live" Monday ... the day after he formally announces his bid to make a move to 1600 Pennsylvania Ave.

Buttigieg has a plan if Trump goes low ... confront and disengage.

The Mayor will tackle a variety of issues on "TMZ Live", from courting voters who may have predisposed views of gays, to the consequences people should face if they cheat to get their kids into college.

And, hint ... he plays a respectable guitar!!!