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The 24-year-old from Newport beat Charly Suarez of the Philippines on a split decision in his opening bout on day one of competition.
Cordina will face Hurshid Tojibaev of Uzbekistan in the round of 16 on Tuesday (15:30 BST).
"They had it as a split decision but I thought I won every round," he said.
"The first one is normally my shaky one and it was against a tough opponent in Charlie Suarez."
The 2015 European champion expects another tough contest against the 26-year-old Tojibaev who has fought as a professional and qualified for the Olympics through AIBA Pro Boxing ranking.
The Uzbek scored a unanimous points win over Hakan Erseker of Qatar in his first bout.
"As soon as the draw came out I said I have one of the hardest routes of anyone in the 60kg," added Cordina.
"But you have to beat them all to win the gold and that's what I'm planning on doing.
"I know a bit about Tojibaev and I've seen a couple of his bouts and I'm more than capable of beating him.
"He's going to be very wary of me because I'm a European champion. It is what it is and the best man will win on the day.
"Being the European champion everyone is going to be looking at me as well as the likes of the Cubans and the Russians - it's good."
Welsh boxer Joe Cordina believes he has got his "shaky" first fight out of his system and has set his sights on lightweight gold in Rio.