The veteran lock played 20 minutes for the Bulls franchise in their 26-19 Super Rugby warm-up loss to the Stormers and said he felt fit and ready to add to his 110 Springbok caps, the last of which came at the World Cup in New Zealand.
"There are obviously many people out there that want me to fail, but I don't let it affect me," Matfield told South Africa's Rapport newspaper.
"Physically, I'm in better shape today than I was in 2011 when I retired. I don't have any pain in my back and knees like back then. I feel first class.
"I'm convinced that I'm still good enough to play for the Boks. I'm as fit as ever. Since my retirement, I never stopped training and at the Bulls' practices, I give some of the younger guys a run for their money."
Matfield worked with current South African coach Heyneke Meyer between 2002 and 2007 when the latter led the Bulls and says their shared history played a role in his decision to return to the game.
Meyer replaced Pieter de Villiers as coach of the national team in Jan. 2012, by which time Matfield had already announced his retirement, something he now regrets.
"If I knew Heyneke Meyer would become Springbok coach then I would never have retired," he said.
Matfield signed a two-year contract with the Bulls on Friday and has targeted playing in the 2015 World Cup in England, which would be his fourth tournament, including helping South Africa to the 2007 title in France.
