Steven Fletcher has said that his confidence increased while playing for "really good man-manager" Martin O'Neill during his time at Sunderland.
The Republic of Ireland manager spent just over a year with the Black Cats from December 2011 to March 2013, signing the Scotland international during his spell.
Ahead of Scotland's Euro 2016 qualifier against O'Neill's side, Fletcher told the Daily Record: "He gave me self-confidence, really. He's a really good man-manager as well as on the training pitch. He took you aside, always went out of his way to speak to you, filled you with confidence.
"Unfortunately during that spell at Sunderland I picked up an injury with Scotland that kept me out for six months, and he got the sack before I came back. I was really disappointed with how that ended because obviously he showed a lot of faith in me by paying so much money for me.
"I wanted to work more with him but I never got the chance."
The Republic of Ireland host Scotland next Saturday.
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