Sinner came into the contest on Rod Laver Arena having won all 13 of his previous Grand Slam meetings against players from the United States and the Italian made a quick start and never looked back as Giron’s hopes faded with the setting sun.
“Every match has its own difficulties,” said Sinner, who produced 35 winners but also had 37 unforced errors in a little over two hours of action.
“I struggled to return the first serve. I have room to improve but every win is great in these conditions. I’m happy to be in the next round.”
The top seed saved a late break point and then served an ace to take the first set in only 34 minutes, before shrugging off a series of uncharacteristic errors on his forehand in the next to extend his lead in the match with a rasping winner.
World number 46 Giron pulled back a break early in the next set but a foot injury left him unable to move freely and Sinner got his nose in front again and closed out a comfortable victory on serve.