However, the 23-year-old responded with a birdie on the last to card an opening four-under-par 68, with Hovland returning a 69 and McIlroy struggling to a level-par 72.
“The 17th was a little bit stupid but other than that I felt like I hit the ball great and gave myself a few chances, especially on the back nine where it’s a little bit more scoreable,” Aberg said.
“Overall, I’m really happy with the way I played. I was very nervous this morning, it would have been weird if I wasn’t, but playing with Rory and Viktor was a lot of fun.”
Aberg only turned professional in June after a stellar amateur career, but won the final Ryder Cup qualifying event in Switzerland and was given a wild card by Europe captain Luke Donald the following day.
McIlroy declared on Wednesday that he was now at the front of the Aberg “bandwagon” after partnering him in a practice round in Rome two days earlier, while Hovland joined Justin Rose in labelling him a “stud”.
“The way he’s played the last couple of months, he has not been a pro very long but he certainly doesn’t look scared of the moment,” Hovland said. “I think this week is a great experience for him but I think he’s ready regardless.”
Denmark’s Marcus Helligkilde held the clubhouse lead on eight under par after carding 10 birdies and two bogeys in a 64, while defending champion Shane Lowry and Tommy Fleetwood both shot 69.
“I got off to a great start, three under through seven, and a couple of bogeys around the turn wasn’t great, but I think the course is playing a little bit more difficult this year,” Lowry said.
“There’s a lot more rough and it’s a little bit firmer so three under is not a bad score.”