Northern Ireland's Rory McIlroy was the first of the Europeans on the range, followed by Paul Casey, Thorbjorn Olesen, and Jon Rahm.
Team Europe is hoping to win back the title from Team USA after the Americans' victory in 2016, and further dent the USA's overall Ryder Cup lead. Team USA has won 26 Cups, with Team Europe claiming 13.
"It's great to be back", Molinari said at a press conference on Tuesday morning. "It's not the nicest feeling to watch it from home. I've worked really hard to get back here and I can't wait for the week to get started."
English veteran Ian Poulter, who missed out last time around at Hazeltine in 2016, said he hopes his experience can help guide the team to victory.
"My job this week is to have a level of experience in that team room to help those guys through this week", Poulter said.