Tiger Woods provided the rare bright spots for the United States as the International Team enjoyed their best ever opening session at the Presidents Cup.
The Internationals ended the day 4-1 up at Royal Melbourne – the largest lead they have ever had at the end of day one, beating the 3 and a half-1 and a half lead they had in 1998, the only time they have won the Cup, which was also in Melbourne.
Woods made six birdies – three on the opening five holes – with the International pair never ahead.
"Tiger was working so well between the two of us today. He played great," Thomas said on the PGA website.
"I mean, I just didn't really take advantage of the opportunities, but that's what you have a partner for.
"It was awesome. It's nice knowing when I step up on a par three or a par four that I feel free just because I know he's playing well, and he did."
Every other match went the Internationals' way though.
Sungjae Im and Adam Hadwin beat Patrick Cantlay and Xander Schauffele 1up; Byeong Hun An and Adam Scott beat Tony Finau and Bryson DeChambeau 2 and 1; Hideki Matsuyama and CT Pan beat Patrick Reed and Webb Simpson 1up; and Abraham Ancer and Louis Oosthuizen defeated Gary Woodland and Dustin Johnson 4 and 3.
American struggles could now see Woods play more than expected over the weekend and he has already put himself in the line-up for Friday's foursomes alongside Thomas, with the pair due to face Hun An and Matsuyama.