The 26-year-old will play his first Origin match in 1071 days in Sydney on Wednesday night after recovering from nerve damage to his shoulder.
After almost two years out of the NRL, Flegler returned for the Dolphins in stellar fashion and has been a major factor in their surge into the top eight.
"I'm incredibly proud of him, to think where he has come from and those dark days of thinking his career could be over," Civoniceva told AAP.
"To see the fight he has shown and the work he has done to be back on the field, let alone the Origin arena, is a credit to him and a credit to the Dolphins' medical staff.
"It is a wonderful reward for all that self-belief and I can't wait to see him on Wednesday night. It is a testament to his courage and commitment."
Civoniceva was one of Origin's most uncompromising forwards and played an incredible 33 games for the Maroons, his last when he was 36 and still going strong.
"I love his toughness. He's a real firebrand and a bit of a throwback to the old school with the mongrel that he plays with," Civoniceva said.
"No doubt he will see his role as an important one as a forward leader. Flegs and big Tino (Fa'asuamaleaui), Lindsay Collins and Patty Carrigan have a big responsibility in that forward pack, but it is one I know they will get done."
Flegler has won all three Origin games he has played for the Maroons. Those performances have not been forgotten, but Queensland coach Billy Slater picked Flegler because he knows he will get the job done.
Even so, the phone call to the Dolphins enforcer was one of the most moving the coach has had to make.
"Big Tommy, it's a great story, isn't it? I had a few phone calls with players making their debuts, but Tommy was probably the most emotional on both ends of the phone call," Slater said.
"Everyone knows his journey with his shoulder. Prior to that shoulder injury, he was one of the best front-rowers in the game.
"What he was doing for the Broncos and then for the Dolphins was outstanding, and the way he played for Queensland."
Flegler's qualities are what Slater most admires.
"For him to fight tooth and nail to get back on the field, that speaks volumes of who Tom Flegler is," Slater said.
"He was brought up on a banana farm, he's a tough lad and we're going to need that toughness.
"I love what Tom Flegler brings to his footy team."Â
