The 29-year-old, who has captained the Irish in place of Coleman in recent fixtures, has been the focus of some Hoops fans’ ire during a difficult season that saw rivals Rangers canter to the league title and has also been subjected to horrific abuse on social media.
Duffy, who lost his starting berth at Celtic, joined up with his international team-mates this week and has a good chance of starting against Serbia in Belgrade this evening.
Veteran full-back Coleman is backing the on-loan Brighton centre-back to put his domestic season woes behind him.
He said: “Shane Duffy is a warrior, Shane Duffy is a leader, I think all us Irish people have seen that over the years with his performances.
He's not had the easiest time in Scotland. I've watched the games that he's played and I don't think Shane is the reason why things aren't going the way they wanted up there, there's a lot of other reasons for it, I’m sure.”
Duffy has been targeted by trolls on Instagram taunting him about the death of his father last summer, and Coleman believes the Derry-born defender should be applauded for putting club and country before anything.
The Everton right-back continued: “I don't know if he'll mind me saying this or not, but Shane’s dad passed away last summer and not long after, he was straight back on a ‘plane for Brighton and up to Celtic, and they're the little things that I don't think people take into account.
"I don't know if he will even have had the opportunity to mourn his dad properly. This football bubble is so important.
"A lot of that has to be taken into account and we all need to bear that in mind because the lad would do anything for his club and country.
"He doesn't sulk, he's a great character around the place, he's a warrior and he had a tough time, and jumped on a ‘plane to get back to work, maybe quicker than most people would. I think he has enough credit in the bank for us to keep supporting him."