The four-time major champion holed out an approach shot for an eagle en route to a four-under 67 for a share of the clubhouse lead in the opening round of the Italian Open on Thursday at the Marco Simone club outside Rome.

After producing only one birdie on his opening nine holes - having started his round on the back nine - McIlroy shot up the leaderboard when he landed his second shot from 115 yards on the par-four third a few feet from the hole. 

The ball then rolled in and McIlroy lifted his arms in delight as he watched from afar back up the fairway.

 “That eagle obviously ignited something and sort of kick-started my round a little bit,” said McIlroy, who was five under on his final seven holes.

“I played some really good golf on the way in. I played the more difficult nine well and the easier nine not so well, so probably evened out. Just need to tidy up a few things going into the next few days.”

McIlroy was tied for the lead with five other players - Gavin Green, of Malaysia, Spain's Adri Arnaus, Scotland's Scott Jamieson, England's Eddie Pepperell and France's Antoine Rozner.

US Open champion Matt Fitzpatrick was one stroke ahead at five under through 15 holes, when play was suspended because of darkness.

Defending champion Nicolai Hojgaard, who played in a group with McIlroy and two-time Italian Open champion Francesco Molinari, finished one stroke behind the leaders.

McIlroy finished first and second, respectively, in his previous two tournaments, the Tour Championship in Atlanta and the European Tour's PGA Championship in Wentworth, England, last week.

“If I can get the ball in the fairway the next three days, I should have a chance,” he said.

From September 29 to October 1 next year, Marco Simone will become the third venue in continental Europe to host the Ryder Cup after Valderrama in Spain (1997) and Le Golf National in France (2018).

Ryder Cup captain Luke Donald and vice captains Thomas Bjorn and Edoardo Molinari are expecting feedback from McIlroy and others on how to set up the course to Europe's advantage.

Donald, Bjorn, the Molinari brothers, McIlroy, Viktor Hovland, Fitzpatrick and Tyrrell Hatton all ate dinner together on Wednesday.

"It was good to catch up and talk about the golf course," McIlroy said.

Leading the Australian challenge was 49-year-old Scott Hend, who was two under after 13 holes when he had to come off the course because of the light.

Lucas Herbert completed his 18 holes in a one-under 70, while Jason Scrivener was level par after 13.

- With AAP.