Im Sung-jae, An Byeong-hun and CT Pan enjoyed winning starts in their Presidents Cup debuts as an inspired International Team stunned the United States 4-1 in the opening day's fourballs at Royal Melbourne Golf Club in Australia on Thursday.

South Korea's Im produced a glorious chip-in eagle on the first hole as he and Canadian partner Adam Hadwin edged Xander Schauffele and Patrick Cantlay 1-up in the second match.

An, a late call-up to replace the injured Jason Day, teamed with home hero Adam Scott to defeat Bryson DeChambeau and Tony Finau 2&1, while Pan and Japanese star Hideki Matsuyama earned a fourth point for Ernie Els' team with a thrilling 1-up win over Patrick Reed and Webb Simpson.

Louis Oosthuizen and Abraham Ancer, one of seven debutants in the team, also delivered a point for the Internationals.

US playing captain Tiger Woods and Justin Thomas won the first point of the session with a 4&3 win over Marc Leishman and Joaquin Niemann.

This is the first time since 2005 that the Internationals, whose solitary Presidents Cup win came at Royal Melbourne in 1998, have led after the first round.

South African legend Els still holds Royal Melbourne's course record (60), and the 21-year-old Im credited his captain's expert knowledge for his flying start.

"Surprisingly I wasn't too nervous. I was going to hit a 3-iron off the tee but Ernie came up and advised me to hit a driver since the pin was to the left and obviously it worked out really well. I'm really happy about my results and I'm excited for tomorrow," said Im, who will partner Cameron Smith in Friday's foursomes against Gary Woodland and Rickie Fowler.

"I feel like our teamwork was great. When I wasn't playing well, Adam (Hadwin) would cover for me and vice versa. I think our teamwork really helped make our match great."

An was delighted to start his first Presidents Cup on a winning note alongside Scott.

"It was crazy. I was a little bit nervous. It was fun playing in front of a home crowd, and then playing with Adam calmed me down a lot, and that's why I was able to hit some great shots in the first couple of holes," said the Korean.

"We got in the mood and got some birdies going. Overall we played great. When he's not playing well the first couple holes, I had him covered, and when I was struggling in the middle, he got some birdies going," said An.

Pan was the last pairing out on course as he and Matsuyama fought tooth-and-nail against Reed and Simpson.

The 28-year-old said watching highlights of the International Team's 1998 victory on Wednesday night had rallied the squad.

"The video, even after last night, I watched it a couple of times because I loved it. It's been 21 long years, and I know it's day one, but we still have a lot of work to do. That video definitely pumped and excited everyone on the team," said Pan.

"It's incredible, especially the last match to finish on 18, as well. The crowd are absolutely amazing and the people, the feeling, it's making me like speechless. Yeah, I played great. We're very happy to earn this point."

With their match tied through 16 holes, Matsuyama drained a 28-foot birdie on 17 to regain a 1-up lead and burst into a fist-pump celebration which ignited one of the loudest cheers of the day.

"Hideki, he's such a clutch putter. I was close but he made that tough putt. That was so crucial," said Pan.

Li Haotong has also been left out of Friday's foursome pairings, but Els proclaimed the first Chinese mainland player to be selected for the Presidents Cup would be "raring to go" on Saturday.