Nerves had to dissipate quickly, however, once Miami's Jose Reyes led off the game and sent a popup to Cozart.
"When I got called up last year, the first ground ball was hit to me, and [the nerves] kind of went away after that, knowing that the game is the same," Cozart said. "Once I caught the popup, it was, 'Hey, it's just another game. Time to play.'"
Cozart had the benefit of already making a great first impression following his first big league callup on July 7. He batted .324 in 11 contests, including hits in each of his first seven games, before a season-ending left elbow injury required Tommy John surgery. He also had right ankle surgery in September.
An offseason of rehab resulted in Cozart coming to camp at 100 percent again, and it put him on the inside track to earn the regular shortstop's job. He backed up the confidence when he batted .345 in Spring Training and the led the club with 20 hits and seven doubles. Defensively, he impressed just as much, with plays that ranged from steady to spectacular.
While Duffy was the last rookie to start at shortstop for Cincinnati, Dave Concepcion did it as a rookie in 1970, and his career would be much more memorable. After Concepcion, Hall of Famer Barry Larkin took over. Since then, it's been pretty much a revolving door at the position.
Last season, the job was Paul Janish's, but he struggled at the plate, as well as uncharacteristically in the field. Veteran Edgar Renteria didn't fare any better. Renteria wasn't brought back and Janish is beginning this season at Triple-A Louisville.
"I [told] him, 'I need some more life out of shortstop.'" Reds manager Dusty Baker said during the final week of camp. "He's doing it."
Being a young guy at one of the most important defensive positions is a big responsibility. Bring it on, Cozart thought.
"I like it," Cozart said. "That's something that is fun, to be out there at shortstop, being an important guy communicating and getting to know your pitchers. It's a challenge as a young guy coming in, being in charge."
Baker added another layer of responsibility to Cozart's load by not hiding him in the lineup. Cozart is batting second, and he will be charged to be unselfish by thinking first about moving the runners and setting the table for No. 3 hitter Joey Votto.
Veterans have accepted Cozart and enjoy seeing him be comfortable in his own skin as a Major Leaguer.
"I saw it last year when he came up," said Reds utility infielder Miguel Cairo, who is 37. "I saw the confidence and how he handled himself in the field. And when he takes at-bats, he takes good at-bats, and that's what you want. It's hard to find players that young, or the first time they get to the big leagues, that have that confidence. It's good to see that."
Cozart got through an eventful first day of the season, and like his teammates, earned a Friday off-day to recharge.
"I've never been through this before, especially in Cincinnati," Cozart said. "It's obviously a big deal with the tradition here. Hearing that I'm the first rookie shortstop since Frank Duffy from a long time ago puts pressure on you. But it's good pressure."