A fiery reception is likely to be in store for the 33-year-old, who angered many Latics supporters when he left the club for the Reds on February 25.
Johnson, who returns to Oldham alongside his first-team coach and ex-Latics winger Tommy Wright, is preparing to run the gauntlet, but believes his in-depth knowledge of the club’s squad could prove a trump card tomorrow afternoon.
The former Bristol City and Yeovil midfielder gave a host of second chances in the game to a number of Oldham players who were effectively on the scrapheap after leaving rival clubs and knows the group’s strengths and weaknesses at first hand.
He is confident he can successfully tap into that knowledge to Barnsley’s advantage this afternoon with the Reds - who haven’t conceded a goal in over seven-and-a-half hours - attempting to continue their rousing march to the play-offs with a sixth successive League One victory.
Making no bones about the fact he believes Barnsley will possess an advantage tomorrow afternoon, Johnson added: “I think it does. There’s no doubt it gives you an advantage.
“ I know their strengths and weaknesses, technically, tactically and mentally as well, more importantly.
“I’d be a liar if I didn’t say that. I will certainly be playing on certain parts of it because I want to win.”